Backpacking Jargon

Backpacking Jargon logo; backpacker in Grand Teton National Park

Backpacking: Camping and hiking while carrying almost everything needed in a backpack
Jargon: Expressions used by a group that are hard for others to understand
Backpacking Jargon: Simple explanations of jargon used by backpackers in America

“When I use a word,” Humpty Dumpty said
in rather a scornful tone,
“it means just what I choose it to mean —
neither more nor less.”
Lewis Carroll, Through the Looking Glass

 A    B    C    D    E  

 F    G    H    I    J  

 K    L    M    N    O  

 P    Q    R    S    T  

 U    V    W    X    Y  

 Z   0-9

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A-frame: Tent with two straight poles at each end, forming two legs of a triangle (link)

ABC: Airway, Breathing, and Circulation, old memory aid for highest-priority first aid problems, now ABCDE (link)

ABC watch: Wristwatch that displays Altitude, Barometric pressure, and Compass headings (link)

ABCDE: Airway, Breathing, Circulation, Decision to maintain spine control, Expose life threatening injuries, memory aid for highest-priority first aid problems (link)

ac: Acre, about 0.4 ha or an American football field without end zones (link)

Access trail: Also feeder trail, connects main trail to a trailhead or another trail (link)

Acclimatization: Ascending slowly while getting used to high altitude, to prevent acute mountain sickness or worse (link)

ADT: American Discovery Trail, 6,800 mile (10,900 km) route from the Atlantic Ocean in Delaware to the Pacific Ocean in California (link)

ADZPCTKO: Annual Day Zero Pacific Crest Trail Kick Off, no longer held (link)

AFAIK: As Far As I Know (link)

Al: Aluminum or aluminium (link)

Alcohol stove: Stove that burns alcohol (link)

ALDHA: Also ALDHA-East, Appalachian Long Distance Hikers Association (link)

ALDHA-West: American Long Distance Hiking Association West (link)

Alpine start: Begin hiking well before sunrise to avoid rockfall and other hazards as the day warms (link)

Alpine zone: Above treeline in high-elevation areas (link)

Alternate: Different trail connected to the main trail at each end (link)

Altimeter: Device that measures altitude using air pressure (link)

Altitoots: Farting because of high altitude (link)

AMC: Appalachian Mountain Club (link)

AMS: Acute Mountain Sickness, headaches, vomiting, and more caused by altitudes above 8,000 feet (2,400 m) (link)

Anemometer: Device that measures wind speed (link)

Anker: Brand of battery packs popular with thru-hikers (link)

AQI: Air Quality Index, higher numbers are worse (link)

Aquamira: Brand of liquid two-part chemical water treatment (link)

Arc’x: Arc’teryx, company that makes backpacking gear (link)

As the crow flies: Most direct path between two points, versus by trail or road (link)

AT: Appalachian Trail, 2,200-mile (3,500 km) trail through the Appalachian Mountains from Georgia to Maine (link)

ATA: Appalachian Trail Alliance (link)

ATC: Appalachian Trail Conservancy, formerly Appalachian Trail Conference (link)

Atmospheric river: Also pineapple express, narrow band of airborne moisture causing intense rain and snow storms along the west coast of North America (link)

Avalanche: Dangerous, sudden, and rapid downward flow of snow on a slope (link)

Avalanche beacon: Also avy beacon, small radio transmitter and receiver worn while traveling through avalanche areas to aid rescue (link)

AYCE: All You Can Eat, feature of restaurants popular with thru-hikers (link)

AYH: American Youth Hostels (link)

AZT: Arizona Trail, 800-mile (1,300 km) trail across Arizona from Mexico to Utah (link)



Backboard: long, narrow, rigid board with straps used to carry an injured person (link)

Backcountry: Area with no maintained roads and few buildings or residents (link)

Bacon stretcher: Mythical device designed to stretch bacon (link)

Bald: Low forested mountain without trees on top (link)

Barometer: Device that measures air pressure (link)

Base layer: Innermost clothing, usually intended to quickly move moisture away from the skin (link)

Baxter: Baxter State Park in Maine, north end of the Appalachian Trail (link)

BBQ: Barbecue (link)

Beanie: Also toque, warm knit cap (link)

Bear bag: Bag used to hang food out of reach of bears (link)

Bear box: Bear-resistant locker for food storage (link)

Bear burrito: Sleeping bag or hammock with a smelly backpacker inside, usually cowboy camping (link)

Bear cable: Cable permanently installed high between trees or poles for hanging bear bags (link)

Bear can: Bear-resistant food container carried by backpackers (link)

Bear fortune cookie: Tent (link)

Bear piñata: Suspended bear bag low enough for bears to reach (link)

Bear spray: Canned pepper spray used to discourage actively charging bears (link)

Bearmuda triangle: Keep stored food, kitchen, and sleep area at least 100 yards (meters) apart (link)

Beaver fever: Giardia infection (link)

BeiDou: Chinese satellite navigation system like GPS (link)

Bench: Long flat area on the side of a hill (link)

Bergschrund: Also schrund, crevasse formed at the top of a glacier, often quite deep (link)

Berm: Long pile of dirt on the outer edge of a trail (link)

Beta: Recent first-hand information (link)

Bidet: Device used to squirt water and clean up after pooping, instead of using toilet paper (link)

Big three: Backpack, sleep system (like a sleeping bag and pad), and shelter (like a tent) (link)

Bite valve: Mouth-operated valve on the end of a tube leading to a hydration bladder (link)

Bivouac: Sleep outside without a shelter in bad weather (link)

Bivy sack: Separate lightweight cover around a sleep system (link)

Black blazer: Someone who obscures or blacks-out blazes to prevent other hikers from finding a trail (link)

Black ice: Thin slippery coating of clear ice on rocks, sidewalks, and roads (link)

Blackflies: Small biting flies found in large swarms in the eastern U.S. (link)

Blaze orange: Bright orange color worn during hunting season to reduce accidental shootings (link)

Blaze: Carved or painted mark on a tree or rock, showing the route (link)

Bliss index: Scale of 1 to 10 measure of backpacker happiness, where 10 is best (link)

BLM: Bureau of Land Management, U.S. Government agency managing over 386,000 square miles (over 1,000,000 km²) for multiple uses (link)

Blow out: Serious hiking shoe failure requiring repair or replacement (link)

Blowdown: Trees fallen across a trail or wide area after high winds (link)

Blue bagging: Carrying poop out of the backcountry in blue WAG bags (link)

Blue blaze: Spur trails off the Appalachian Trail marked by blue blazes (link)

Blue-blazer: Backpacker who uses blue-blazed Appalachian Trail sections instead of white-blazed (link)

Bluebird day: Day with blue, cloudless skies (link)

BLUF: Bottom Line Up Front, conclusion at the top with details below. (link)

Bluff: Short cliff (link)

BMT: Benton MacKaye Trail, 288-mile (463 km) trail from Georgia to North Carolina (link)

Boardwalk: Trail segment covered with planks to protect sensitive areas (link)

Bog bridge: Also puncheon, narrow walkway to protect wetlands (link)

Bomber: Unusually strong or durable gear; also a good rock climbing hold (link)

Bonk: Suddenly run out of personal energy due to lack of blood sugar (link)

Bonus miles: Extra distance backpacked on a thru-hike without forward progress, like hiking to a town and back for resupply (link)

Book time: Guidebook time to complete a trail (link)

Bounce box: Also drift box or flyer, package of thru-hiker supplies not needed soon, so shipped ahead (link)

BPL: Backpacking Light, online publication with active community forums (link)

BPW: Base Pack Weight, also baseweight, total weight of backpack with everything inside except consumables like food, water, and fuel (link)

Brain: Backpack lid with a zippered pocket (link)

Break trail: Flatten a path through fresh snow that others can follow easier (link)

Breathable: Fabric ability to pass water vapor (link)

Bridge hammock: Hammock with bars on both ends creating a flatter sleeping surface (link)

Brown blazing: Off trail detour to poop (link)

BRP: Blue Ridge Parkway, National Park unit in North Carolina and Virginia (link)

BSA: Boy Scouts of America (link)

BSI: Big Sky International, company that makes backpacking gear (link)

BSL: Big SEKI Loop, 155-mile (249 km) route through Sequoia and Kings Canyon National Parks, California (link)

BTDT: Been There, Done That, direct experience with the subject (link)

Bubble: Also pack or herd, main group of thru-hikers moving along a trail, typically spread out across several days (link)

Bucket list: List of adventures to complete before “kicking the bucket” (dying) (link)

Buffer zone: Protected areas adjacent to the Appalachian Trail. (link)

Bushwhack: Difficult hiking through dense bushes and branches (link)

Bypass: Skip a trail segment, town, or trailside attraction (link)



c: Cup, about 240 ml, exactly 8 ounces volume (link)

C: Celsius, metric measure of temperature, 0 °C is 32 °F (link)

Cache: pronounced cash, food and supplies hidden for later pick up (link)

Cairn: Also duck, tall rock pile that might indicate the trail path (link)

Calorie loading: Eating lots of high calorie food during a town stop (link)

CalTopo: Website and app for mapping and navigating backcountry adventures (link)

Camel up: Also tank up, drink a lot of water at a water source (link)

Camp clean: Clean enough but not that clean (link)

Canister stove: Backpacking stove that burns pressurized butane-propane fuel in metal cans (link)

Canopy: Top layer of a forest (link)

Canyoneering: Also canyoning, traveling the length of rugged canyon bottoms by rock climbing and swimming (link)

Can’t see the forest for the trees: Foreground features hide important background features (link)

Carbs: Carbohydrates, major part of most backpacker diets, including sugary foods, pasta, couscous, and tortillas (link)

Caretaker: Also maintainer, person who maintains a permanent shelter or campsite (link)

Cat hole: Small hole dug to dispose of poop (link)

Catenary curve: Natural curve that rope or fabric makes while suspended between two points (link)

CBS: Cold Butt Syndrome, when hammock campers sleep without enough insulation below them (link)

CCF: Closed Cell Foam, dense plastic foam used for sleeping pads and backpack padding (link)

CDT: Continental Divide Trail, 3,100-mile (5,000 km) trail through the Rocky Mountains from Mexico to Canada (link)

CFM: Cubic Feet per Minute, about 7.5 gallons per minute or 28 liters per minute (link)

CFS: Cubic Feet per Second, about 7.5 gallons per second or 28 liters per second (link)

Chafing: Pain and redness where skin rubs together or gear rubs skin, aggravated by sweat and dirt (link)

Chinook winds: Warm southwest winds on the coast of Oregon and Washington; also warm west winds on the eastern slope of western North American mountain ranges (link)

Chrome dome: Brand name of a discontinued lightweight reflective umbrella, now used for all similar umbrellas (link)

Christmas toes: Tingling and numbness in thru-hiker toes that lasts through December 25 (link)

ci: Cubic inch, about 16.4 ml; 1,000 ci is about 16 liters (link)

Cirque: Also corrie or cwm, steep-sided mountain valley with closed upper end (link)

Class 1 climb: Trail hiking (link)

Class 2 climb: Low-risk scrambling, sometimes using hands (link)

Class 3 climb: Higher-risk scrambling, handholds needed, rope sometimes used to stop falls (link)

Class 4 climb: Simple rock climbing, rope often used to stop falls, unroped falls may be fatal (link)

Class 5 climb: Technical rock climbing, rope usually used to stop falls, unroped falls typically fatal (link)

Class I rapid: Short, fast river section with small waves and no obstacles (link)

Class II rapid: Short, fast river section with easily avoided obstacles (link)

Class III rapid: Short, fast river section with irregular waves, tight channels, and multiple maneuvers required (link)

Class IV rapid: Short, fast river section with unavoidable large waves, critical maneuvers required, and stopping for inspection usually required (link)

Class V rapid: Long dangerous river section, stopping for inspection difficult, and difficult rescues (link)

Cliffed out: Off-trail route that becomes too steep to proceed safely (link)

Clo: Clothing insulation measurement, about 1.55 togs or R 0.88 (link)

ClO2: Also ClO2, chlorine dioxide, chemical water disinfectant (link)

cm: Centimeter, about 0.4 inches (link)

CO: Carbon monoxide, colorless odorless poisonous gas, formed by flames or combustion without enough oxygen (link)

Cobbknocker: Also webwalker, web face, or web master, first person on a trail who clears spider webs (link)

Col: Also gap, notch, or sag, low point on a ridge (link)

Cold soak: Prepare food by soaking it in water without cooking (link)

Comfort hiker: Backpacker carrying much more weight in the pursuit of camping comfort (link)

Companion: ALDHA Thru-hikers Companion, guidebook for the Appalachian Trail (link)

The Complete Walker: Popular 1968 book by Colin Fletcher that dramatically expanded interest in backpacking (link)

Contour lines: Curved lines on a map representing constant elevations (link)

Contouring: Also sidehilling or slabbing, following a roughly constant elevation path around a mountain or canyon (link)

Cornice: Dangerous overhanging ledge of snow and ice on a ridge or peak (link)

Corridor: Narrow strip of land along both sides of a trail (link)

COSPAS-SARSAT: International organization that uses government satellites to locate PLB rescue signals and trigger rescues (link)

Cotton world: Off-trail life, when wearing cotton is not potentially life-threatening (link)

Cove: Small bay or coastal inlet; also small valley in the Appalachian Mountains, closed at one or both ends (link)

Cowboy camp: Sleep out in the open, without a tent or shelter (link)

Cowboy coffee: Mixture of hot water and ground coffee carefully poured unfiltered into a cup (link)

Cowboy water: Also dip-and-sip, drink water directly from the source without treatment (link)

Cowtaminated: Water source polluted by cattle waste (link)

CPR: Cardiopulmonary respiration, first aid for reviving a few mostly dead patients (link)

Crampons: Metal frame with spikes and straps, used on boots for climbing steep ice (link)

Crevasse: Deep, dangerous crack in a glacier that can be hidden by a weak snow bridge (link)

Croo: Caretakers of Appalachian Mountain Club huts (link)

Crotch gusset: Small fabric panel in pants allowing more range of motion (link)

Crotch rot: Inflammation and often infection around the genitals (link)

Crushing miles: Also pushing miles, hiking much farther than usual each day (link)

Crypto: Cryptosporidium, waterborne intestinal parasite that causes diarrhea (link)

CT: Colorado Trail, 490-mile (780 km) trail through the Rocky Mountains from Denver to Durango, Colorado (link)

Culvert: Water passage under a trail or road, made of pipe, rock, or wood (link)

Cupholders: Backpack lower side pockets used to carry water bottles (link)

Cushy: Comfortable (link)

CX: Cross-country, also freehike, hike a path not on established trails (link)

CYTC: Calendar Year Triple Crown, complete the PCT, CDT, and AT in one year between January 1 and December 31. (link)



D: Denier, pronounced den-year, measure of thread and fabric density, higher is heavier (link)

Daisy chain: Two-layered webbing with one layer sewn to leave open loops, used for hammock suspensions; also a long rope gathered using interlocking loops (link)

DAM: Down-filled Air Mattress, inflatable sleeping pad insulated with down (link)

Data Book: Appalachian Trail information published by the ATC (link)

DCF: Dyneema Composite Fabric, fabric made with Dyneema (link)

DCH: Dyneema Composite Hybrid, fabric made with DCF, bonded to layers of other materials (link)

Dead branch tattoo: Also rock tattoo or trail tattoo, scar acquired while hiking (link)

Dead fall: Dead tree laying across a trail (link)

Death march: Long, boring hike, often in hot weather (link)

Declination: Also magnetic declination, difference between true north and magnetic north (link)

DEET: Type of insect repellant applied to skin (link)

Deets: Details (link)

Diablo wind: Strong, hot, dry offshore wind in Central California (link)

DIAD: Done In A Day (link)

Dialed-in: Describes gear well matched to the task (link)

Dirtbagging: Backpacking on a limited budget using ragged gear (link)

Dispersed camping: Camping away from established campsites and trails (link)

Ditty bag: Small bag to hold miscellaneous items (link)

DIY: Do It Yourself (link)

DOC: Dartmouth Outing Club (link)

Dodgeway: Fence opening that permits hikers to pass, not livestock (link)

Dome tent: Shelter shaped roughly like the upper half of a ball or geodesic dome (link)

Double blaze: Two aligned vertical blazes indicating a sharp trail turn (link)

Double-track: Primitive dirt road formed by parallel vehicle tires (link)

Double-triple: Completing the Triple Crown twice (link)

Double-wall: Tent with two layers of fabric overhead, outer layer waterproof (link)

Down in the weeds: Focused on details, missing larger features (link)

Down the rabbit hole: Getting deep into a topic, sometimes ending up somewhere strange (link)

Droppin trou: Said to others before lowering shorts, pants, or trousers outdoors (link)

Drumlin: Long low hill formed by glaciers (link)

Dry camp: Camp overnight without using local water (link)

Duct tape: Also Duck Tape brand name, wide, heavy duty tape used for repairs and other tasks (link)

Duff: Layer of leaves, sticks, and other dead plant material covering the ground (link)

DWR: Durable Water Repellant, coating that helps rain run off fabric for a while (link)

Dyneema: previously Cuben, brand of UHMW polyethylene fibers (link)



EABO: Eastbound thru-hiker (link)

ECT: Eastern Continental Trail, 4,400 mile (7,100 km) route from Key West, Florida to Belle Isle, Newfoundland (link)

EE: Enlightened Equipment, company that makes backpacking gear (link)

EGNOS: European Geostationary Navigation Overlay Service, satellite system that improves Galileo navigation accuracy in Europe, like WAAS and GPS in North America (link)

Elk duds: Elk poop that resembles Milk Duds candy (link)

EMS: Emergency Medical Services like paramedics and ambulances; also Eastern Mountain Sports outdoor retailer. (link)

EN rating: Also sleeping bag rating, unreliable sleeping bag low temperature estimate using the ISO 23537 standard, formerly EN 13537 (link)

End-to-ender: Someone completing the entire Appalachian Trail (link)

ESBIT: Brand of hexamine solid fuel tablet (link)

Escape velocity: Courage to leave a vortex (link)

Escarpment: Long series of cliffs, roughly the same height and same direction (link)

EtOH: Ethanol, drinking alcohol (link)

Exposure: Description of steep area with high risk of falling and serious injury or death, more exposure is more dangerous (link)

External frame pack: Backpack with stiff supports near your back and outside the fabric (link)

Extension collar: Extra-tall backpack body for carrying more stuff (link)

Eyelet: Shoelace hole in a boot or hiking shoe, often reinforced with metal or plastic (link)



F: Fahrenheit, U.S. measure of temperature, 32 °F is 0 °C (link)

Facilatrees: Forest as toilet or “facilities” (link)

FAK: First Aid Kit (link)

Fall line: Shortest and steepest way down a hill (link)

False lead: Path that looks like the real trail, but is not (link)

False pass: Mountain crossing that looks like the true pass until you get there (link)

False summit: High spot that looks like the true summit until you get there (link)

FarOut: Formerly Guthook, brand of app-based guides to long-distance trails (link)

Fastpacking: Covering many miles (km) per day with a very light backpack (link)

FBC: Freezer Bag Cooking, preparing food by adding hot water to ingredients inside a thick zippered plastic bag (link)

Fill power: Measure of down insulation fluffiness, higher is lighter (link)

First-hand experience: Personally observed or participated in the subject (link)

FKT: Fastest Known Time, speed record for hiking a trail end to end (link)

Flash flood: Rapid flooding of low lying areas, often scouring desert washes and slot canyons in sunny conditions (link)

Flip-flop: Thru-hike part of a trail in one direction, then skip ahead to hike another part in the other direction (link)

Floater: Tiny debris suspended in water (link)

Floorless: Tent without a built-in floor (link)

Flophouse: Cheap town lodging for thru-hikers (link)

Florida Trail: A 1,500 mile (2,400 km) trail following most of the length of Florida (link)

Food fantasies: Backpacker dreams of what they will eat in town (link)

Footprint: Separate floor underneath a tent for added protection (link)

Ford: Cross a river by wading through the water (link)

Four state challenge: Hike the Appalachian Trail across Virginia, West Virginia, Maryland, and Pennsylvania in less than 24 hours (link)

Frameless: Backpack without an internal or external frame (link)

Freestanding tent: Tent that mostly works without stakes in the ground (link)

FSO: From Skin Out, total pack weight plus everything worn or carried (link)

ft: Foot, about 30.5 cm, exactly 12 inches (link)

ft³: Also ft3, cubic foot, about 7.5 gallons or 28 liters, exactly 1,728 cubic inches (link)

Fun factor: Current (lack of) enjoyment, part of evacuation decisions after illness or injury (link)

FWIW: For What It’s Worth, slightly off-topic but still important (link)

FWOT: Freaking Waste Of Time, project or path that seriously fails to meet expectations (link)

FWS: Fish and Wildlife Service, U.S. Government agency managing over 235,000 square miles (over 600,000 km²) to protect wildlife (link)



g: Gram, about 0.035 ounces weight (link)

GAIA GPS: App for mapping and navigating backcountry adventures (link)

Gaiters: Lower leg and shoe coverings to protect from dirt, water, snow, and obnoxious plants (link)

Galileo: European satellite navigation system like GPS (link)

Gallon: 3.79 liters, exactly 4 quarts (link)

GAMEr: Northbound Appalachian Trail thru-hiker traveling from Georgia to Maine (link)

Garvey: Double vertical blaze with the top blaze pointing to a trail turn (link)

GAS: Gear Acquisition Syndrome, problem of buying too much backpacking gear (link)

Gathered end: Hammock with each end gathered for suspension (link)

Gathering: Annual ALDHA meetup in New Hampshire or West Virginia (link)

GBITS: Great Backpacker In The Sky, mythical being who tests the toughness of hikers (link)

GCNP: Grand Canyon National Park in Arizona (link)

GDT: Great Divide Trail, 700-mile (1,130 km) trail in the Rocky Mountains along the border of Alberta and British Columbia (link)

Gear attic: Fabric shelf high inside a tent for storing gear (link)

Gear head: Someone very focused on backpacking gear (link)

Gear: Backpacking equipment (link)

Gearly afflicted: Backpacker with Gear Acquisition Syndrome (link)

GET: Grand Enchantment Trail, 770-mile (1,240 km) route across Arizona and New Mexico (link)

Getting off: Temporarily or permanently leaving a thru-hike (link)

GG: Granite Gear or Gossamer Gear, companies that make backpacking gear (link)

Ghost blazing: Following an abandoned trail segment (link)

GGG: Gathering of the Gear Geeks, annual meetup of Backpacking Light gear heads in California; also Garage Grown Gear outdoor retailer (link)

Giardia: Waterborne intestinal parasite that causes giardiasis, including diarrhea, stomach cramps, and vomiting (link)

Glissade: Sliding down steep snow without skis, usually holding an ice axe to stop safely (link)

Globalstar: Satellite system for messaging and phone calls; also a brand of satellite phones (link)

GLONASS: Russian satellite navigation system like GPS (link)

GMC: Green Mountain Club (link)

GNSS: Global Navigation Satellite Systems, like GPS, Galileo, GLONASS, and BeiDou (link)

Go-to gear: Equipment used on most backpacking trips by someone (link)

Going to ground: When a hammock camper decides to sleep on the ground (link)

GORP: Good Old Raisins and Peanuts, also trail mix (link)

GPS: Global Positioning System, U.S. satellite navigation system (link)

GPX: Computer file with waypoints, tracks, routes, elevations, and times (link)

Grade: Trail steepness, higher grades are steeper (link)

Gram weenie: Also weight weenie, someone focused on reducing their backpacking gear weight (link)

Graupel: Also snow pellets, tiny, soft hail that can lead to avalanches later (link)

Gray water: Dirty dishwater (link)

Green tunnel: Most of the heavily-forested Appalachian Trail (link)

Ground control: Off-trail people who help thru-hikers with shopping, shipping, bill paying, and pet care (link)

Groundling: Also ground dweller or grounder, backpackers who sleep on the ground (link)

GSMNP: Great Smoky Mountains National Park in North Carolina and Tennessee (link)

Gully: Also gulch, large ditch to small valley formed by erosion (link)

Gut it out: Keep going despite fatigue, illness, or injuries (link)

Gut rot: Belly pain from bad food or infection (link)

Guylines: Cords used to attach tents and tarps to stakes or other supports (link)

GWL: Great Western Loop, 6,875 mile (11,065 km) route linking the PCT, PNT, CDT, GET, and AZT through nine states (link)

GWT: Great Western Trail, 4,455 mile (7,170 km) trail from Mexico to Canada through Arizona, Utah, Wyoming, Idaho, and Montana (link)



ha: Hectare, about 2.5 acres (link)

HACE: High Altitude Cerebral Edema, life-threatening brain illness caused by altitudes above 8,000 feet (2,400 m) (link)

Half gallon challenge: Eat a half gallon (1.9 liters) of ice cream halfway through the Appalachian Trail (link)

Hammock: Fabric sling hung between trees, just above the ground, for sleeping (link)

Hammock tent: Hammock with everything needed for shelter, including tarp, bug net, and suspension (link)

Hanger: Hammock camper (link)

HAPE: High Altitude Pulmonary Edema, life-threatening lung illness caused by altitudes above 8,000 feet (2,400 m) (link)

Happy camper: Someone happy in their current activity (link)

Hardcore: Very dedicated person (link)

Hardshell: Waterproof jacket or pants without insulation (link)

Harpers Ferry: ATC headquarters town near the Appalachian Trail in West Virginia (link)

Hayduke Trail: 812 mile (1,307) route across Utah and Arizona (link)

HE pot: Also HX pot, Heat exchanger pot, with outer fins to capture more stove heat (link)

Headlamp: Small light attached to a strap, usually worn on forehead or upside-down on neck (link)

Headwall: Cliff at the upper end of a cirque (link)

HEET: Brand of gasoline additive, sometimes used as alcohol stove fuel (link)

Heine pot: Tall Heineken beer can turned into a cook pot (link)

Hermit hiker: Someone who likes to hike alone (link)

HH: Hydraulic head, unreliable measure of fabric water resistance, higher is more waterproof (link)

High Sierra Camps: Permanent backcountry camps in Yosemite National Park, California, with tent cabins, bedding, and hot meals (link)

Highway tree: Fallen tree that allows cross-country hiking over brush (link)

Hiker box: Box or cabinet where thru-hikers donate unwanted stuff (link)

Hiker funk: Persistent odor of thru-hiker clothing and gear after weeks of backpacking (link)

Hiker Heaven: PCT thru-hiker hostel in California (link)

Hiker hunger: Intense hunger and enormous appetite developed while thru-hiking (link)

Hiker midnight: 9 pm (2100 hours), bedtime for many thru-hikers (link)

Hiker shuffle: Awkward thru-hiker steps after removing their backpack at the end of the day (link)

Hiker tan: Dirty skin that resembles a suntan (link)

Hiker trash: Affectionate name for thru-hikers after weeks of backpacking (link)

Hiker-friendly: Town or business that appreciates thru-hikers (link)

Hill-walking: Hiking in the hills (link)

Hitchhike: Also hitch, get vehicle rides from strangers (link)

HMG: Hyperlite Mountain Gear, company that makes backpacking gear (link)

Home free: Very close to the end of a thru-hike (link)

Hostel: Low-cost shared lodging often used by thru-hikers (link)

HST: High Sierra Trail, 49-mile (79 km) trail through Sequoia National Park to Mount Whitney, California (link)

HTD: Horizontal Tree Drip, when condensation drips from trees, then wind blows it into your face or tent vents (link)

HTH: Hope This Helps (link)

Hump: Carry a heavy load (link)

Hut: Also bothy, permanent trail shelter, often shared with other backpackers (link)

Hybrid tent: Combination single-wall and double-wall tent (link)

Hydration bladder: Also water reservoir, flexible water container (link)

Hydration system: Backpack-mounted hydration bladder, hose, and bite valve for hands-free drinking (link)

HYOH: Hike Your Own Hike, resist pressure to hike or backpack like others, not permission to break rules (link)

Hyperthermia: Dangerously high body temperature (link)

Hyponatremia: Dangerously low blood sodium, usually from drinking too much plain water (link)

Hypothermia: Dangerously low body temperature (link)



IANAL: I Am Not A Lawyer, warning that legal advice might not be correct (link)

IAT: International Appalachian Trail, 1,850 mile (2,540 km) trail from the Appalachian Trail north end in Maine to the north tip of Newfoundland (link)

Icebergs: Large rocks placed in overused campsites to prevent camping (link)

ICT: Idaho Centennial Trail, 1,311 mile (2,110 km) trail across Idaho from Nevada to Canada (link)

IERCC: International Emergency Response Coordination Center, company that coordinates responses to satellite communicator rescue messages (link)

IIRC: If I Recall Correctly (link)

IMO: In My Opinion (link)

IMHO: In My Humble Opinion (link)

IMNSHO: In My Not So Humble Opinion (link)

in: Inch, about 2.5 cm (link)

Indian summer: Warm dry autumn weather, typically after a period of cooler weather (link)

inReach: Brand of two-way satellite communicators (link)

Internal frame pack: Backpack with stiff supports near your back and inside the fabric (link)

Iridium: Satellite system for messaging, phone calls, and Internet access (link)

ISO: International Standards Organization, creates and publishes standards (link)



JMT: John Muir Trail, 211-mile (340 km) trail through the Sierra Nevada from Yosemite Valley to Mount Whitney, California (link)

Jungle hammock: Hammock with built-in bug netting (link)



Karst: Eroded limestone landscape with sinkholes, caves, fissures, and towers (link)

Katabatic wind: Wind caused by colder, denser air falling from a higher elevation (link)

Katahdin: Appalachian Trail north end on Mount Katahdin, Maine (link)

KCHBR: Kings Canyon High Basin Route, 124-mile (200 km) route in Sequoia-Kings Canyon National Park, California (link)

kg: Kilogram, about 2.2 pounds (link)

km: Kilometer, about 0.6 miles (link)

km²: Also km2, square kilometer, about 247 acres or 0.4 square miles (link)

Knob: Prominent rounded hill or mountain (link)

Knot: Fixed looping of a rope, guyline, or webbing; common backpacking knots include half hitch, bowline, and taught line hitch (link)

Krumholtz: Stunted and twisted trees found near treeline (link)

Kula Cloth: Brand of pee cloth (link)



L: Liter, about 1 quart or 61 cubic inches (link)

LASH: Long Assed Section Hike, backpack multiple sections of a longer thru-hike (link)

Lash point: Small loop or slots on gear to attach other gear with straps or cord (link)

lb: Pound, about 454 g, exactly 16 ounces weight (link)

LCT: Lost Coast Trail, 25-mile (40 km) trail in California following the Pacific Ocean (link)

Lean-to: Permanent backcountry shelter with slanted roof and open sides (link)

Leapfrog: Repeatedly pass and get passed by the same backpackers while hiking (link)

Learning opportunity: Mistake that you can learn from (link)

Leeward: Also lee, downwind, the direction the wind is going toward (link)

Litter: Trash left in the backcountry; also long, narrow rigid basket used to carry an injured person (link)

LNT: Leave No Trace, guidelines to reduce local environmental impacts while backpacking (link)

Loft: Thickness of fluffed-up insulation, like a sleeping bag ready for use, higher is warmer (link)

Logbook: Also register, trailside paper book to record trail progress and communicate with other hikers (link)

Lollipop: Hike that includes both an out-and-back and a loop (link)

LP: Lone Peak, brand of trail running shoes (link)

Long Trail: 273-mile (439 km) trail through Vermont (link)

The Look: Thru-hiker appearance after weeks of backpacking, with confidence, determination, and a muscular, lean body (link)

Lyme disease: Serious illness transmitted to humans by tick bites (link)

L2H: Lowest to Highest, 130 mile (209 km) route from Badwater to Mount Whitney in California (link)



m: Meter, about 1.1 yards or 3.3 feet (link)

MacGyver: Creatively solve a problem using available materials, from an old TV show (link)

mAh: milliamp hour, vague and confusing battery energy unit, use watt-hours (Wh) instead (link)

Mail drop: Supplies and gear shipped to a thru-hiker for resupply along the trail (link)

Massif: Distinct local group of connected mountains (link)

MATC: Maine Appalachian Trail Club (link)

MEC: Mountain Equipment Company, formerly Mountain Equipment Co-op, outdoor retailer (link)

McLeod: Combination rake and hoe for trail building and firefighting (link)

MEGA: Southbound Appalachian Trail thru-hiker, traveling from Maine to Georgia (link)

Menstrual cup: Small soft reusable cup worn internally to catch menstrual blood, instead of using disposable tampons or pads (link)

Meths: Also methylated spirits, denatured alcohol, often with methanol plus ethanol (link)

Micro USB: Small rectangular connector used for recharging batteries (link)

Mid: Pyramid-shaped tent supported by internal vertical poles (link)

Mile: About 1.6 km (link)

Mineral soil: Ground with almost no burnable material, good for stoves (link)

Misery index: Scale of 1 to 10 measuring backpacker suffering, where 10 is worst (link)

Misting: Water droplets floating inside a tent (link)

ml: Milliliter, about 0.2 teaspoons (link)

MLD: Mountain Laurel Designs, company that makes backpacking gear (link)

Mod: Modify gear after purchase (link)

Modder: Someone who modifies gear (link)

Monkey butt: Red butt inflammation and often infection (link)

Monsoon: Intense summer thunderstorm season in American southwest deserts (link)

Moraine: Ridge of broken rocks formed by glaciers (link)

Mountain money: Also shit tickets, toilet paper (link)

Mountain walking: Hiking in the mountains (link)

Mountains-to-Sea Trail: 1,175 mile (1,891 km) trail from the Great Smoky Mountains to the Atlantic Ocean through North Carolina (link)

Mouse hanger: Cord with can for hanging packs, to prevent mice from entering (link)

MPD: Miles Per Day, 1 mile is about 1.6 km (link)

MRE: Meal Ready to Eat, also Meal Rejected by Everyone, compact well-preserved military food (link)

MRT: Mogollon Rim Trail, 500-mile (800 km) route following the Mogollon Rim escarpment across Arizona (link)

MSR: Mountain Safety Research, company that makes backpacking gear (link)

Moskies: Also muskies or mozzies, mosquitos (link)

Multi-use trail: Trail with multiple uses allowed, like hiking, horseback riding, and mountain biking (link)

MVTR: Moisture Vapor Transfer Rate, poorly-standardized measure of fabric ability to allow humid air to escape, higher allows more (link)

MYOG: Make Your Own Gear, instead of buying gear made by others (link)

MYTH: Multi-Year Thru-Hike, backpacking another part of one long-distance trail, year by year (link)



Nalgene: Brand of water bottle (link)

National Scenic Trail: Eleven significant U.S. trails including the PCT, CDT, and AT (link)

NCT: North Country Trail, 4,800 mile (7,700 km) trail from Vermont to North Dakota (link)

Nero: Short day thru-hiking with just one night in town, nearly a zero day (link)

Nest: Hammock camper setup including hammock, suspension, tarp, and insulation (link)

Nesting: When one pot or cup fits nicely inside another (link)

Newbie: Also noob, someone new to an activity (link)

NNML: Northern New Mexico Loop, 500-mile (800 km) route through New Mexico (link)

No-see-um: Also midge, tiny biting fly; also describes tent netting with holes too small for midges (link)

NOBO: Northbound thru-hiker (link)

NOC: Nantahala Outdoor Center (link)

NOLS: Formerly National Outdoor Leadership School, non-profit school teaching outdoor skills and wilderness medicine (link)

Non-freestanding tent: Tent that needs stakes in the ground to work properly (link)

Nor'easter: Also Northeaster, intense blizzards between November and March from North Carolina to Nova Scotia (link)

NPS: National Park Service, U.S. Government agency that manages over 133,000 square miles (over 340,000 km²) “unimpaired for the enjoyment of future generations” (link)

NWS: National Weather Service, U.S. Government agency that forecasts weather (link)



OCT: Oregon Coast Trail, 425-mile (684 km) trail along the Pacific coast in Oregon (link)

ODT: Oregon Desert Trail, 750-mile (1,207 km) trail across the deserts of eastern Oregon (link)

Off-trail: Hiking a path not on established trails; also the developed world away from a thru-hike (link)

OHT: Ozark Highlands Trail, 320-mile (515 km) trail across northern Arkansas (link)

OIA: Outdoor Industry Association, trade group of outdoor gear manufacturers (link)

Old-growth: Ancient forest or tree not yet logged (link)

On-trail: Hiking on an established trail (link)

OP: Original Post, referring back to the first entry in a forum thread (link)

OR: Outdoor Research, company that makes backpacking gear; also Outdoor Retailer, annual trade show (link)

Oregon challenge: Thru-hike the PCT all the way through Oregon in less than 2 weeks (link)

OTC: Over The Counter, medicines like aspirin that you can buy without a prescription (link)

Out-and-back: Hike out then return on the same trail (link)

Outer tent: Rainfly on a double-wall tent (link)

Outhouse: Also privy, small permanent shelter with a hole in the ground for pooping (link)

oz: Ounce, about 28.4 g weight; also about 28.4 ml volume (link)

Oz: Australia (link)



Pack it out: Leave nothing behind on a backpacking trip (link)

Pack string: Pack animals like horses or mules, tied together and led down the trail (link)

Packing your fears: Carrying more gear and food than needed due to fears and inexperience (link)

Packraft: Also trail boat, one-person, lightweight, inflatable boat designed to be carried and used by a backpacker (link)

Packsplosion: Also full yard sale, emptying a pack and spreading everything out to find something (link)

Pass: Mountain ridge low point, sometimes allowing hiking to the other side (link)

Patagucci: Nickname for Patagonia, company that makes backpacking gear (link)

PBC: Portable Battery Charger, also battery bank, USB brick, and many variations, battery pack for recharging other devices using USB (link)

PCT: Pacific Crest Trail, 2,650-mile (4,270 km) trail through California, Oregon, and Washington from Mexico to Canada (link)

The PCT Hiker’s Handbook: Influential 1992 book by Ray Jardine that re-kindled interest in lightweight backpacking, MYOG, and corn pasta (link)

PCT-L: Pacific Crest Trail email list and archive (link)

PCTA: Pacific Crest Trail Association, issues PCT permits and maintains the trail (link)

PCT Days: Annual Pacific Crest Trail festival in Cascade Locks, Oregon (link)

Peak bagging: Climbing a list of mountain peaks (link)

Pee: Liquid body waste, urine (link)

Pee cloth: Also pee rag, cloth used to wipe body after squatting to pee, then hung outside a backpack to dry (link)

Penalty potatoes: Food carried but not eaten on a trip (link)

Pepsi can stove: Also tin can stove, alcohol or solid fuel stove made from an empty can, like cat food, tuna, or beer (link)

PEU: Also PE, polyether urethane, waterproof fabric coating (link)

PF: Plantar fasciitis, painful foot condition (link)

PFD: Personal Flotation Device, lifejacket (link)

PhD: Posthole Digger, hiker who enjoys postholing through the snow (link)

Piezo igniter: Device that makes electric sparks by clicking a button to light stoves (link)

PIF: Pay It Forward, encourage someone you helped to help someone else in return (link)

Pinhoti Trail: 335 mile (539 km) trail in the Appalachian Mountains through Georgia and Alabama (link)

Pit zips: Jacket armpit zippers allowing more ventilation (link)

PITA: Pain In The Ass, obnoxious person or task (link)

Platypus: Brand of hydration bladders (link)

Playing in the high energy zone: Engaging in outdoor activities with dangerous natural forces, like hiking precarious ridge tops or cornices, or running challenging river rapids (link)

PLB: Personal Locator Beacon, one-time-use device that sends rescue signals through government satellites (link)

Plunge step: Also heel step, hike down a snowy or crumbly slope heel-first, digging in with each step (link)

PNT: Pacific Northwest Trail, 1,200-mile (1,900 km) trail from the Rocky Mountains in Montana to the Pacific Ocean in Washington (link)

PO: Post Office, where thru-hikers send and receive mailed packages (link)

Point: First person in a group of hikers, responsible for finding the way (link)

Polycro: Also polycryo, lightweight plastic sheeting used as tent footprints (link)

Poop: Also poo, semi-solid body waste, feces, excrement, manure (link)

PORE: Point Reyes National Seashore in California (link)

Posthole: Plunge feet and legs deep into snow while hiking (link)

Pot cozy: Insulation around a pot, designed to keep food warm (link)

Potable water: Water clean enough to drink (link)

Potty trowel: Small one-handed shovel for digging cat holes (link)

POUS: People Of Unusual Size, backpackers who are taller than most, adapted from a Princess Bride movie scene (link)

Power hiker: Backpacker who covers many miles per day, often in the dark (link)

PRD: Pocket Rocket Deluxe, an upright canister stove made by MSR (link)

Prescribed fire: Also controlled burn, fire set under supervision to prevent larger wildfires (link)

pt: Pint, about 473 ml, exactly 2 cups or 16 ounces volume (link)

PU: Polyurethane, also polyester urethane, waterproof fabric coating (link)

PUD: Pointless Ups and Downs, also Mindless Ups and Downs, trail segments that seem to climb and drop for no reason (link)

Puffy: Thick down or synthetic insulated jacket (link)

Pulaski: Combination axe and adze for trail building and firefighting (link)

Pull the trigger: Decide to buy a piece of gear after lengthy thinking (link)

Purist: Appalachian Trail thru-hiker planning to pass every white blaze (link)



q: Quart, about 946 ml, exactly 2 pints, 4 cups, or 32 ounces volume (link)

Quad: Also quadrangle, named USGS topographic map covering a rectangular area (link)

Quilt: Hoodless, bottomless sleeping bag (link)

Quiver: Personal collection of similar backpacking gear, like several backpacks (link)



R-value: Standardized measure of sleeping pad insulation, higher is warmer (link)

r/Ultralight: Reddit online ultralight backpacking community (link)

Rain gear: Clothing worn for rain protection, including hat, jacket, gloves or mittens, and pants (link)

Rain shadow: Area with much less rain on the downwind side of a mountain range, often forming deserts (link)

Rainbow blazer: Appalachian Trail thru-hiker who hikes different-colored blazed routes (link)

Rainfly: Also flysheet, waterproof tent fabric designed to shed falling rain and snow (link)

Ramen bomb: Meal combining ramen noodles and instant mashed potatoes (link)

Ray Day: Best date to hike out of Kennedy Meadows on a northbound PCT thru-hike, considering Sierra Nevada snow depths (link)

Ray-way: Backpacking philosophies of author Ray Jardine (link)

Real world: Backcountry or civilization, depending on context, like “back in the real world ...” (link)

Red flag warning: National Weather Service forecast of high fire danger (link)

Red snow: Snow colored by red algae, not safe to eat or drink (link)

REI: Recreational Equipment Inc, very large U.S. outdoor retailer (link)

Relo: Relocated trail segment (link)

Remote canister stove: Stove attached to a short hose, with the hose attached to a fuel canister (link)

Repeat offender: Someone thru-hiking the same long distance trail again (link)

Resupply: When thru-hikers pick up more supplies (link)

RICE: Rest, Ice, Compression, Elevation, memory aid for treating injuries like sprains and broken bones; instead of compression, use support like tape or splints (link)

Ridge runner: Person employed to hike back and forth on trail sections, educating hikers and enforcing rules (link)

Ridgeline: Line following the highest points of a ridge; also a tight guyline above a hammock to maintain desired shape (link)

Ridgerest: Brand of closed-cell-foam sleeping pad that rolls up (link)

Rime ice: Ice formed on trees and other surfaces when windblown water droplets freeze (link)

RMC: Randolph Mountain Club (link)

Rock garden: Part of a trail or river with lots of rocks sticking up (link)

Rock hop: Hop from rock to rock across a river or stream attempting to keep dry (link)

RSN: Real Soon Now, eventually or someday (link)

RUA: Restricted Use Area, backcountry area with special rules (link)

Ruck: Meetup of outdoor enthusiasts (link)



S2S: Sea-to-Summit, company that makes backpacking gear (link)

Safety meeting: Group smoking marijuana together (link)

SAK: Swiss Army Knife, brand of pocket knife with other tools (link)

SAM splint: Brand of shapable but rigid support for suspected broken bones (link)

Santa Ana wind: Strong, hot, dry offshore winds in Southern California (link)

SAR: Search and Rescue, the team and process of finding people and rescuing them (link)

Scat: Animal poop (link)

Scouting: Inspecting the route ahead from a high point along a trail or river; also a worldwide youth movement teaching outdoor activities including backpacking (link)

Scramble: Climb a rugged area using hands and feet, but not rock climbing (link)

Scree: Fist-sized rocks on slopes, difficult to hike over (link)

Seam tape: Special tape added to tent, backpack, or rainwear seams for waterproofing and reinforcement (link)

Second breakfast: Extra morning meal due to hiker hunger (link)

Second dinner: Extra evening meal due to hiker hunger (link)

Section: Portion of a longer thru-hike, usually between towns or major trailheads (link)

Section hiking: Backpacking sections of long trails like the PCT, CDT, or AT (link)

SEKI: Sequoia and Kings Canyon National Park in California (link)

SEND: Satellite Emergency Notification Device, satellite communicator that sends rescue messages through commercial satellites (link)

Shakedown: Gear inspection and suggestions from a more experienced backpacker (link)

Shakedown hike: Backpack trip to test gear and skills before a longer hike (link)

Shale: Loose flat rocks with sharp edges, often difficult to hike over (link)

Shell: Uninsulated outermost clothing (link)

Shelter: Tent or tarp; also small three-sided building for backcountry camping (link)

Shelter rat: Hiker who camps only in permanent shelters. (link)

Shenandoah: Shenandoah National Park in Virginia (link)

Shin-splints: Shin pain from overuse and inflammation (link)

SHR: Sierra High Route, 195-mile (314 km) route above timberline in the Sierra Nevada, California (link)

SHS: Shaky Headlamp Syndrome, annoying lighting changes as your head moves while wearing a headlamp (link)

SHT: Superior Hiking Trail, 310-mile (500 km) trail following the shore of Lake Superior in Minnesota (link)

Shuttle: Paid ride between trailhead and town (link)

Sil/PU: Fabric coated with with silicone on one side, polyurethane on the other (link)

Sil/sil: Fabric coated with with silicone on both sides (link)

Silnylon: Silicone-coated nylon fabric (link)

Silpoly: Silicone-coated polypropylene fabric (link)

Single-track: Narrow trail (link)

Single-point hammock: Also portaledge, hammock that hangs from one overhead point, mostly used for rock climbing (link)

Single-wall: Tent with just one fabric layer (link)

Skipping: Bypassing a section of trail (link)

Skunked: When cars do not stop while hitchhiking by the side of a road (link)

Skyhook: Mythical device for suspending items in midair; also a rock climbing device (link)

Slackpacking: Sending a backpack ahead while hiking without it (link)

Sleep system: Sleeping bag or quilt plus sleeping pad (link)

Slogging: Difficult hiking on a muddy trail (link)

Slot canyon: Long narrow channel eroded into the earth, typically in the southwestern U.S. (link)

SMD: Six Moon Designs, company that makes backpacking gear (link)

Smoke shifter: Mythical device for moving campfire smoke, often requested as left-handed or right-handed (link)

Smokies: Part of the Appalachian Mountains on the border of Tennessee and North Carolina (link)

Snag: Standing dead or dying tree; also large chunks of wood in a river (link)

Snot rocket: Plug one nostril and blow mucus forcefully out the other (link)

Snowpack: Compressed snow layered on the ground, usually from multiple storms, higher snowpack is deeper (link)

SNP: Shenandoah National Park in Virginia (link)

SOBO: Southbound thru-hiker (link)

Social trail: Also use trail, unofficial trail formed by repeated walking (link)

Softshell: Wind and water resistant insulated jacket or pants, not waterproof (link)

Soloing: Backpacking alone (link)

SOS: Emergency signal requesting help or rescue (link)

Spectra: Brand of UHMW polyethylene fibers (link)

Speed hiking: Hiking rapidly down a trail pursuing a new record (link)

Spork: Combination spoon and fork in one utensil (link)

SPOT: Brand of satellite phones and satellite communicators (link)

Springer fever: Desire by previous thru-hikers to return to the Appalachian Trail (link)

Springer Mountain: Appalachian Trail south end in Georgia (link)

Spruce trap: Spruce tree covered by deep snow, dangerous to fall into (link)

sq mi: Also mi² or mi2, square mile, about 259 ha, exactly 640 acres (link)

Square meter: Also or m2, about 1.2 square yards or 10.8 square feet (link)

Square yard: Also yd² or yd2, about 0.84 square meters, exactly 9 square feet (link)

Stats: Statistics and details (link)

Stealth camping: Camping well off trail at an unofficial site, while practicing Leave No Trace (link)

Stick snake: Stick that jumps up and hits you when you step on it (link)

Stile: Steps passing over a fence that permit hikers to pass, not livestock (link)

Stoveless: Backpacking without a stove, usually eating cold food (link)

Stupid light: Gear too light to function well; also not carrying enough to reach goals or stay safe (link)

SUL: Super Ultra Light, base pack weight less than 5 pounds (2.2 kg) (link)

Summit: Also peak, top of a mountain (link)

Sun cups: Uneven snow surface like the inside of a giant egg carton, hard to hike over (link)

Suspension: Straps, ropes, and hardware needed to hang a hammock between two anchors (link)

Swag: Lowest connection between two ridges (link)

Swale: Dip in a trail designed to shed water (link)

Swamp ass: Sweaty butt, can cause chafing and monkey butt (link)

Sweep: Last hiker in a group, makes sure no one falls behind (link)

Switchback: Sharp trail turn on a slope to make climbing and dropping easier but longer, and reduce trail erosion (link)



Talus: Large broken rocks that usually do not move as you step on them (link)

TAR: Therm-a-Rest, brand of backpacking gear (link)

Tarn: Mountain lake or pond scooped out by a glacier (link)

Tarp: Simple overhead fabric shelter with no floor or doors (link)

tb: Tablespoon, about 15 ml (link)

TBD: To Be Determined, specification or answer will be supplied later (link)

TBI: Traumatic Brain Injury, serious head injury typically caused by a hard impact (link)

TD: Trail Designs, company that makes backpacking gear (link)

Teardown: Completely disassemble a piece of gear, often documenting the process with photos (link)

Tehachapi challenge: Hike the Pacific Crest Trail from Hiker Town to Tehachapi in less than 24 hours (link)

Ten essentials: Short list of items day hikers should carry for safety (link)

Tenkara: Minimalist fly-fishing without a reel (link)

Tent body: Inner fabric layer of a double-wall tent (link)

Tent platform: Flat wooden stage or dirt pad for camping (link)

Three-season: Gear and skills for spring, summer, and fall backpacking, loosely defined (link)

Thru-hiking: Long, multi-day backpacking that requires resupply and usually starts and ends in different places (link)

Ti: Titanium (link)

Ticks: Tiny blood-sucking parasites that can transmit Lyme disease and other serious infections (link)

TNF: The North Face, company that makes backpacking gear (link)

Tog: Clothing insulation measurement, about 0.645 clo or R 0.57 (link)

Togs: Clothing (link)

Top quilt: Quilt used on top of a hammock camper or groundling (link)

Topo: Topographic map with contour lines of constant elevation; also a brand of trail running shoes (link)

Torso pad: Short sleeping pad just long enough to reach from head to butt (link)

Town clothes: Clothing worn by thru-hikers while in town (link)

Town gut: Belly pain after thru-hikers eat too much in town (link)

TP: Toilet Paper, used to wipe your butt after depositing poop, instead of using a bidet (link)

TPW: Total Pack Weight, combined mass of everything carried in a backpack (link)

Trail angel: Someone who provides trail magic to thru-hikers (link)

Trail clearing: Removing trail obstacles for easier passage (link)

Trail Days: Annual Appalachian Trail festival in Damascus, Virginia (link)

Trail gorilla: Volunteer who helps maintain the PCT (link)

Trail legs: Stronger, almost tireless legs of thru-hikers after weeks of backpacking (link)

Trail magic: Unexpected help or supplies provided to thru-hikers (link)

Trail muffin: Horse manure on a trail (link)

Trail name: Nickname traditionally given to a backpacker on their first thru-hike (link)

Trail provides: Thru-hiker belief that when they really need something, it will appear (link)

Trail runners: Lightweight trail-running shoes used instead of boots (link)

Trail spice: Leaves, twigs, and dirt in backpacking food (link)

Trail spikes: Flexible set of metal spikes that attach to trail shoes for hiking on ice-covered trails (link)

Trail town: Hiker-friendly towns near popular long-distance trails (link)

Trail virgin: First time thru hiker (link)

Trailhead: Trail segment start and end, typically a parking lot or road (link)

Tramily: Trail family, group of thru-hikers who bond and travel together (link)

Tramper: Hiker, especially one who continues despite bad weather (link)

Traverse: Move horizontally across a slope; also travel the length of a mountain range, island, or named region (link)

Tread: Bottom of a shoe or boot that contacts the ground; also the surface of a trail (link)

Treadway: Constructed surface of a trail (link)

Treeline: Maximum elevation or latitude where trees strop growing, replaced by shorter plants (link)

Trekking: Hiking, usually long-distance hiking (link)

Trekking poles: Also hiking poles or hand wands, hand-held poles used for hiking stability and pushing forward (link)

Triage: Sort multiple sick or injured patients into a few priority levels (link)

Triangulation: Determine position using compass bearings to three landmarks like mountain peaks (link)

Triple Crown: PCT, CDT, and AT (link)

TRT: Tahoe Rim Trail, 175 mile (281 km) trail around Lake Tahoe in California (link)

ts: Teaspoon, about 5 ml (link)

TSA: Transportation Security Administration, U.S. Government agency with rules about what you may not take on an airplane, enforced through inspections at airports (link)

TST: Theodore Solomons Trail, 271 mile (437 km) trail in the Sierra Nevada, roughly parallel to the John Muir Trail at lower elevations (link)

TT: Tarptent, company that makes backpacking gear (link)

Turnpike: Also highway or freeway, heavily used trail (link)

Type 1 fun: Traditional fun, enjoyable during the experience (link)

Type 2 fun: Miserable experience that seems like fun later, worth repeating (link)

Type 3 fun: Terrible experience, usually requiring rescue or emergency medical care, avoid repeating (link)

TYT: Tahoe-Yosemite Trail, 186 mile (299 km) route from Lake Tahoe to Yosemite National Park in California (link)

Tyvek: Brand of waterproof polyethylene fabric (link)



UHMW: Also UHMWPE, Ultra-High-Molecular-Weight Polyethylene, very strong, lightweight, plastic fibers used in fabrics and guylines, like Dyneema and Spectra (link)

UL: Ultralight, base pack weight less than 10 pounds (4.5 kg) (link)

Underquilt: Quilt hung just below a hammock for insulation from cold air (link)

Understory: Shorter trees and bushes growing beneath a taller forest (link)

Undulating trail: Climbs up and down like a series of waves. (link)

Unobtainium: Mythical substance that solves all problems (link)

Upright canister stove: Stove attached directly to the top of a fuel canister (link)

USB-A: Rectangular connector used for recharging batteries (link)

USB-C: Oval connector used for recharging batteries (link)

USFS: United States Forest Service, U.S. Government agency that manages over 300,000 square miles (over 780,000 km²) for multiple uses (link)

USGS: United States Geological Survey, U.S. Government agency that makes topographic maps and measures river flows (link)

UV: Ultraviolet, invisible sunlight that can tan skin and cause cancer (link)

UV-C: Ultraviolet light that can sterilize water (link)



VBL: Vapor Barrier Liner, waterproof inner clothing or sleeping bag liner used in temperatures below freezing (link)

Vestibule: Sheltered tent entrance, often used to store gear (link)

Virga: Visible rainfall that evaporates before reaching the ground (link)

Vitamin I: Ibuprofen, non-prescription medicine for pain and inflammation (link)

Vortex: Place that thru-hikers find hard to leave, like a town, restaurant, or hot springs (link)



W: Watt, standard unit of electrical power, not energy (link)

WAAS: Wide-Area Augmentation System, satellite system that improves GPS accuracy in North America (link)

Waffle-stompers: Heavy boots with lugged soles that leave waffle-like patterns on trails (link)

WAG bag: Waste Aggregation and Gelling bag, used to carry poop out of heavily used backcountry areas (link)

Walk-in: Developed campsites reserved for backpackers or bicyclists (link)

Walk-up: Easy mountain summit, no more than Class 2 climbing (link)

War wounds: Injuries earned while hiking (link)

Washout: Also blowout, portion of trail destroyed by flooding or erosion (link)

Water math: Calculating how much water to carry between possibly unreliable sources (link)

Water report: Water source information posted online by other thru-hikers, especially on the PCT and CDT (link)

Waterbar: Log or rock barrier that directs water off a trail to prevent erosion (link)

Waterproof: Fabric or container that resists the entry of water (link)

Watershed: Landscape that channels all the rain, melted snow, and groundwater feeding into one stream or river (link)

WEBO: Westbound thru-hiker (link)

Weekend warrior: Also weekender, backpacker camping for 1 to 4 nights (link)

WEMT: Wilderness Emergency Medical Technician, training and certification for backcountry medicine (link)

Wet out: Saturated waterproof breathable fabric that stops breathing, then condensation builds up inside (link)

WFA: Wilderness First Aid, training and certification for basic backcountry first aid (link)

WFR: Wilderness First Responder, also woofer, training and certification for advanced backcountry first aid (link)

Wh: Watt-hour, standard unit of electrical energy, not power (link)

White blaze: Blaze that marks the one true Appalachian Trail (link)

White blazer: Thru-hiker following only white blazes on the Appalachian Trail (link)

Whites: White Mountains of New Hampshire (link)

Whoopie sling: Lightweight hammock suspension adjusted using hollow rope sliding through itself (link)

Widowmaker: Dead tree or large limb that could fall and injure or kill a backpacker (link)

Wilderness area: Highly protected roadless U.S. public lands, over 170,000 square miles (over 440,000 km²) (link)

Williwaw: Blast of cold wind dropping from the mountains (link)

Wind direction: Compass direction the wind blows from, so an east wind blows from the east to the west (link)

Wind layer: Outer clothing to protect from wind (link)

Windchill: Additional cooling caused by wind (link)

Windchill factor: Lower felt temperature computed from measured temperature and wind speed (link)

Windjacket: Jacket to protect from wind (link)

Windpants: Pants to protect from wind (link)

Windward: Upwind, the direction the wind is coming from (link)

WM: Western Mountaineering, company that makes backpacking gear (link)

WMI: Wilderness Medicine Institute, now NOLS Wilderness Medicine, teaches backcountry first aid and medicine (link)

Wonderland Trail: 93-mile (150 km) trail around Mount Ranier in Washington (link)

WPB: Waterproof Breathable, fabric that might be waterproof and breathable (link)

WRHR: Wind River High Route, 95-mile (153 km) route across the Wind River mountain range in Wyoming (link)



XUL: Extreme Ultra Light, base pack weight even less than SUL (link)



Yard sale: Backpacking gear unpacked and spread out, usually for drying (link)

yd: Yard, about 91 cm, exactly 3 feet (link)

Yellow blaze: Yellow center-line on a highway (link)

Yellow blazer: Someone who hitchhikes around trail sections (link)

Yellow snow: Snow colored by urine, not safe to eat or drink (link)

YKK: Brand of zippers (link)

YMG: Yama Mountain Gear, company that makes backpacking gear (link)

YMMV: Your Mileage May Vary, worked for me, might not work for you (link)

YNP: Yosemite National Park in California (link)

Yogi-ing: Letting strangers offer food and drink without asking directly, like the cartoon character Yogi Bear (link)

Yo-yo: Hike a long trail in one direction, then turn around and hike back to the start (link)

Yurt: Round semi-permanent tent-like shelter (link)



Z Lite: Brand of closed cell foam sleeping pad that folds up (link)

Zero day: Day with no miles thru-hiked, two nights in the same town for rest and resupply (link)

Zero-mile: Beginning of a trail that might not be at a trailhead, like Springer Mountain for the Appalachian Trail (link)

Zoleo: Brand of two-way satellite communicators (link)



10 by 10: 10 miles (about 16 km) by 10 am, strategy for hiking more distance per day (link)

20, 25, 30, 40: Planned mileage today, like “hiking a 30”, 1 mile is about 1.6 km (link)

2000-miler: Successful Appalachian Trail thru-hiker (link)

911: Emergency phone number for the U.S., Canada, and several other countries, like 999 or 112 elsewhere (link)


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Answering “What does that mean?” in clear, simple words. Designed for backpackers in America unfamiliar with some expressions, which might be regional or trail-specific. These are not comprehensive definitions, and many entries have other meanings, depending on context. All trail lengths are approximate and subject to change.

Goals: Created by Rex Sanders, CC BY-SA 4.0
868 entries as of 2023 January 10