1. (Anat.)

Defn: An air sac, sometimes double or variously lobed, in the visceral cavity of many fishes. It originates in the same way as the lungs of air-breathing vertebrates, and in the adult may retain a tubular connection with the pharynx or esophagus.

2. A sac or bladder full of air in an animal or plant; also an air hole in a casting.

AIR BRAKE
Air" brake`. (Mach.)

Defn: A railway brake operated by condensed air. Knight.

AIR BRUSH
Air brush.

Defn: A kind of atomizer for applying liquid coloring matter in a spray by compressed air.

AIR-BUILT
Air"-built`, a.

Defn: Erected in the air; having no solid foundation; chimerical; as, an air-built castle.

AIR CELL
Air" cell`.