Definition of 'air sac'
air sac in British
noun
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. Copyright © HarperCollins Publishers
air sac in American
any of the air-filled cavities in a bird's body, having connections to the lungs
Webster’s New World College Dictionary, 4th Edition. Copyright © 2010 by
Houghton Mifflin Harcourt. All rights reserved.
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Source
Definition of air sac from the
Collins English Dictionary
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