airsac

Definitions of air sac in various dictionaries:

noun - a tiny sac for holding air in the lungs

noun - any of the thin-walled extensions of the tracheae of insects

noun - any of the membranous air-filled extensions of the lungs of birds

AIR SAC - One of the spaces in different parts of the bodies of birds, which are filled with air and connected with the air passages of the lungs; an air cell.