air sac 气囊
air sac[ noun ]- a tiny sac for holding air in the lungs; formed by the terminal dilation of tiny air passageways
<noun.body>
- any of the thin-walled extensions of the tracheae of insects
<noun.animal>
- any of the membranous air-filled extensions of the lungs of birds
<noun.animal>
Air sac \Air" sac`\
1. (Anat.) 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.
2. An {alveolus}.
[PJC]