sinus: Meaning and Definition of

si•nus

Pronunciation: (sī'nus), [key]
— pl. -nus•es.
  1. a curve; bend.
  2. a curving part or recess.
    1. any of various cavities, recesses, or passages, as a hollow in a bone, or a reservoir or channel for venous blood.
    2. one of the hollow cavities in the skull connecting with the nasal cavities.
    3. an expanded area in a canal or tube.
  3. a narrow passage leading to an abscess or the like.
  4. a small, rounded depression between two projecting lobes, as of a leaf.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.
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