Common wildfire terms, by the U.S. Forest Service:

Aerial fuels: All live and dead vegetation in the forest canopy or above surface fuels, including tree branches, twigs and cones, snags, moss, and high brush.

Air tanker: A fixed-wing aircraft equipped to drop fire retardants or suppressants.

Backfire: A fire set along the inner edge of a fireline to consume the fuel in the path of a wildfire and/or change the direction....

Blow-up: A sudden increase in fire intensity or rate of spread strong enough to prevent control or to upset control plans. Blow-ups are often accompanied by violent convection and may have other characteristics of a firestorm. (See Flare-up.)

Brush fire: A fire burning in vegetation that is predominantly shrubs, brush and scrub growth.

Candle, candling: A single tree or a very small clump of trees burning from the bottom up.

Contain a fire: A fuel break around the fire has been completed....

Control a fire: The complete extinguishment of a fire, including spot fires....

Control line: All built or natural fire barriers and treated fire edge.

Creeping fire: Fire burning with a low flame and spreading slowly.

Crown fire, crowning: The movement of a fire through the crowns of trees or shrubs more or less independently of the surface fire.

Defensible space: An area either natural or manmade where material capable of causing a fire to spread has been treated, cleared, reduced, or changed to act as a barrier between an advancing wildland fire and the loss to life, property, or resources. In practice, "defensible space" is...a minimum of 30 feet around a structure....

Direct attack: Any treatment of burning fuel, such as by wetting, smothering, or chemically quenching the fire or by physically separating burning from unburned fuel.

Escape route: A preplanned and understood route firefighters take to move to a safety zone or other low-risk area....

Fire break: A natural or constructed barrier used to stop or check fires that may occur, or to provide a control line from which to work.

Fire perimeter: The entire outer edge or boundary of a fire.

Fire shelter: An aluminized tent offering protection by reflecting radiant heat and providing a volume of breathable air.... Fire shelters should only be used in life-threatening situations as a last resort.

Flanks: The parts of a fire's perimeter that are roughly parallel to the main direction of spread.

Flare-up: Any sudden acceleration of fire spread or intensification of a fire. Unlike a blow-up, a flare-up lasts a relatively short time and does not radically change control plans.

Flash fuels: Fuels such as grass, leaves, draped pine needles, fern, tree moss and some kinds of slash that ignite readily and are consumed rapidly when dry. Also called fine fuels.

Ground fuel: All combustible materials below the surface litter, including duff, tree or shrub roots, punchy wood, peat, and sawdust, that normally support a glowing combustion without flame.

Hand line: A fireline built with hand tools.

Head of a fire: The side of the fire having the fastest rate of spread.

Hotshot crew: A highly trained fire crew used mainly to build firelines by hand.

Hotspot: A particular active part of a fire.

Incident commander: Individual responsible for the management of all ...operations.

Knock down: To reduce the flame or heat on the more vigorously burning parts of a fire edge.

Prescribed fire: Any fire ignited by management actions under certain, predetermined conditions...

Pulaski: A combination chopping and trenching tool which combines a single-bitted axe-blade with a narrow trenching blade fitted to a straight handle. Useful for grubbing or trenching in duff and matted roots. Well-balanced for chopping.

Radiant burn: A burn received from a radiant heat source.

Red flag warning: Term used by fire weather forecasters to alert forecast users to an ongoing or imminent critical fire weather pattern.

Retardant: A substance or chemical agent which reduced the flammability of combustibles.

Run: The rapid advance of the head of a fire with a marked change in fire line intensity and rate of spread....

Safety zone: An area cleared of flammable materials used for escape....

Scratch line: An unfinished preliminary fire line hastily established or built as an emergency measure to check the spread of fire.

Slash: Debris left after logging, pruning, thinning or brush cutting; includes logs, chips, bark, branches, stumps and broken understory trees or brush.

Smokejumper: A firefighter who travels to fires by aircraft and parachute.

Spot fire: A fire ignited outside the perimeter of the main fire by flying sparks or embers.

Staging area: Locations set up at an incident where resources can be placed....

Suppressant: An agent, such as water or foam, used to extinguish the flaming and glowing phases of combustion....

Surface fuels: Loose surface litter on the soil surface, normally consisting of fallen leaves or needles, twigs, bark, cones, and small branches that have not yet decayed enough to lose their identity; also grasses, forbs, low and medium shrubs, tree seedlings, heavier branchwood, downed logs, and stumps interspersed with or partially replacing the litter.

Torching: The ignition and flare-up of a tree or small group of trees, usually from bottom to top.

Underburn: A fire that consumes surface fuels but not trees or shrubs.

Wet line: A line of water, or water and chemical retardant, sprayed along the ground, that serves as a temporary control line from which to ignite or stop a low-intensity fire.