air sac

Definitions of air sac
  1. noun
    a tiny sac for holding air in the lungs; formed by the terminal dilation of tiny air passageways
    synonyms: air cell, alveolus
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    type of:
    sac
    a structure resembling a bag in an animal
  2. noun
    any of the membranous air-filled extensions of the lungs of birds
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    type of:
    sac
    a structure resembling a bag in an animal
  3. noun
    any of the thin-walled extensions of the tracheae of insects
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    type of:
    sac
    a structure resembling a bag in an animal
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