Those wildland areas where the combination of vegetation, topography, weather, and the threat of fire to life and property create difficult and dangerous problems.

A number representing the chance that a given event will occur. The range is from 0% for an impossible event, to 100% for an inevitable event.

The agency or jurisdictional facility from which resources are allocated to incidents.

A combination chopping and trenching tool widely used in fireline construction, which combines a single-bitted axe blade with a narrow adze-like trenching blade fitted to a straight handle.

A parachute designed and rigged for dropping equipment and supplies from an aircraft.

The fuel moisture content, weighed over all the fuel classes, at which the fire will not spread.

Angle or bearing 180 degrees opposite of azimuth.

Ignition of fuels by dropping incendiary devices or materials from aircraft.

Sawing through the bole of a tree after it has been felled.

Unit of fluid viscosity in fire retardant, defined as tangential force per unit area (dynes/square centimeter) required to maintain unit difference in velocity (1 centimeter/second) between two parallel planes separated by 1 cm of fluid (1 poise=1 dyne-second/cubic centimeter).