air sac   (TTS Sound)

The noun air sac has 3 senses

• alveolus, air sac, air cell -- (a tiny sac for holding air in the lungs; formed by the terminal dilation of tiny air passageways)


• air sac -- (any of the thin-walled extensions of the tracheae of insects)


• air sac -- (any of the membranous air-filled extensions of the lungs of birds)