(literally) Air that has been heated, especially so as to function as the lifting agent of a hot-air balloon. / (idiomatic) Empty, confused, or exaggerated talk lacking meaning or substance; bluster.

Vehicle suspension in which compressed air is used as a spring.

A mattress that is inflated with air, and used as a temporary or permanent bed.

A bed that is inflated with air and used as a permanent or temporary bed. They are adjustable, and sometimes portable.

Alternative letter-case form of air marshal (found when the term is used as a title).

Alternative letter-case form of air commodore (found when the term is used as a title).

Alternative spelling of air conditioner

A machine that is used to control temperature and humidity in an enclosed space.

(chemistry, historical) Oxygen gas, as originally thought to be air deprived of phlogiston (“the hypothetical fiery principle formerly assumed to be a necessary constituent of combustible bodies and to be given up by them in burning”).

A device used to remove contaminants from the air.