A hole in any surface that allows air or other gases to pass, especially an opening in the surface of a frozen lake etc. / An air pocket. / The blowhole of a whale.

(military) A military airport, providing housing and support for aircraft and personnel.

(military) The act of using aircraft to attack an enemy to assist ground military forces.

The middle of the air, as while in flight.

To assuage a hostile situation.

Alternative spelling of airbag.

The contamination of the atmosphere by noxious gases and particulates.

Alternative spelling of airburst

A mixture of hydrogen and air used as fuel to a fuel cell. / (obsolete, chemistry) An early term for hydrogen; hydrogen gas.

(physics, meteorology) The gravity-induced downslope flow of relatively cold air. Winds thus produced are called gravity winds.