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Medical Term:


Pronunciation: sī′nŭs, -ĕz


  1. A channel for the passage of blood or lymph, without the coats of an ordinary vessel; blood passages in the gravid uterus or those in the cerebral meninges.
  2. A cavity or hollow space in bone or other tissue.
  3. A dilation in a blood vessel.
  4. A fistula or tract leading to a suppurating cavity.

[L. sinus, cavity, channel, hollow]