air-sac

air sac

noun
1.
a sac containing air.
2.
alveolus ( def 2 ).
3.
any of certain cavities in a bird's body connected with the lungs.
4.
a saclike dilation of the wall of a trachea in many insects.

Origin:
1820–30

Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
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Collins
World English Dictionary
air sac
 
n
1.  any of the membranous air-filled extensions of the lungs of birds, which increase the efficiency of gaseous exchange in the lungs
2.  any of the thin-walled extensions of the tracheae of insects having a similar function

Collins English Dictionary - Complete & Unabridged 10th Edition
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American Heritage
Medical Dictionary

air sac n.
A tiny, thin-walled, capillary-rich sac in the lungs where the exchange of oxygen and carbon dioxide takes place. Also called alveolar sac.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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American Heritage
Science Dictionary
air sac  
  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 enlargement in the trachea of an insect.

  4. 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 © 2002. Published by Houghton Mifflin. All rights reserved.
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