The admission of a proper supply of fresh air, esp. to a room, building, mine, or other place where the air readily becomes stagnant and…

The action of the verb in various senses; ventilation.

Originally: the process of cleaning air and controlling its temperature and humidity in connection with certain manufacturing processes. Now…

air conditioning of multiple rooms in a building by a single air conditioning unit, typically using a series of ducts (frequently attributive)…

= central air conditioning n.

(a) n. air conditioning; (b) adj. air-conditioned.

= air conditioning, n.

U.S. Chiefly in classified advertisements: air conditioning, esp. in a car or other vehicle. Cf. central air n. at central, adj. compounds.