Actual physical engagement in firefighting service as distinguished from staff work at headquarters or maintenance division; work at an individual fire done by an individual firefighter or by a company.

Rapid oxidation, usually with the evolution of heat and light; heat fuel, oxygen and interaction of the three.

Net attached to the cargo hook of a helicopter, used to carry cargo.

Application of prescribed fire.

Shut-off nozzle that permits the nozzle operator to open or close the nozzle or adjust the pattern of the stream.

A fire in progress or under investigation.

A tapered thread standard that is used for connecting various sizes of rigid pipe. This standard may be referred to as tapered iron pipe thread (TIPT), National pipe thread (NPT), iron pipe thread (IPT), or iron pipe standard thread (IPS). With tapered thread, the threads and pipe sealant perform the seal at the connection. This is opposed to straight thread connectors which use a gasket to form the seal. 

A wildland fuel that is suspended off the ground in such a way that fire may burn both over and under it.

Burning material at the points deliberately ignited for backfiring, slash burning, prescribed burning, and other purposes.

Level, in the vicinity of the fire, at which the smoke ceases to rise and moves horizontally with the wind at that level.