air sac
Share:
Tweet n. 1. An air-filled space in the body of a bird that forms a connection between the lungs and bone cavities and aids in breathing and temperature regulation. 2. See alveolus. 3. A saclike, thin-walled enlargement in the trachea of an insect. 4. An inflatable pouch attached to the larynx in certain mammals, including the nonhuman great apes. |
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2022 by HarperCollins Publishers. All rights reserved.