- a sac containing air.
- alveolus(def 2).
- any of certain cavities in a bird's body connected with the lungs.
- a saclike dilation of the wall of a trachea in many insects.
Origin of air sac
First recorded in 1820–30
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Examples from the Web for air sac
These animals are said to possess an air-sac in the throat, at the back of the trachea (or windpipe), as in Ateles.A Hand-book to the Primates, Volume 1 (of 2)
Henry O. Forbes
- any of the membranous air-filled extensions of the lungs of birds, which increase the efficiency of gaseous exchange in the lungs
- any of the thin-walled extensions of the tracheae of insects having a similar function
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
- A tiny, thin-walled, capillary-rich sac in the lungs where the exchange of oxygen and carbon dioxide takes place.alveolar sac
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
- 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.
- See alveolus.
- A saclike enlargement in the trachea of an insect.
- A baglike piece of skin or tissue below the jaw of certain animals, such as the bullfrog and orangutan, that can be inflated to increase sound production.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.