from The American Heritage® Dictionary of the English Language, 5th Edition.

  • noun A depression or cavity formed by a bending or curving.
  • noun A dilated channel or receptacle containing chiefly venous blood.
  • noun Any of various air-filled cavities in the bones of the skull, especially one communicating with the nostrils.
  • noun Medicine A fistula leading from a pus-filled cavity.
  • noun Botany A recess or indentation between two lobes or segments, as of a leaf.

from The Century Dictionary.

  • noun A bend or fold; a curving part of anything; a sinuosity; specifically, a bay of the sea; a gulf.
  • noun In anatomy and zoology, a cavity or hollow of bone or other tissue, in the widest sense; a bay, recess, pocket, dilatation, or excavation, generally deeper and less open than a fossa: used with either English or Latin context.
  • noun In pathology, a narrow passage leading to an abscess or other diseased locality; a fistula.
  • noun In botany, the recess or rounded curve between two projecting lobes: as, the sinuses of a repand or sinuate leaf. See cuts under kidney-shaped, pinnatifid, repand, and sinuate.
  • noun The bony air-sinuses of the head. See def. 2 .
  • noun The rhombocœlia. Also called sinus rhomboidalis.
  • noun one of the sinuses of the dura mater (see above), or
  • noun a sinus venosus (see above).

from the GNU version of the Collaborative International Dictionary of English.

  • noun An opening; a hollow; a bending.
  • noun A bay of the sea; a recess in the shore.
  • noun (Anat. & Zoöl.) A cavity; a depression.
  • noun A cavity in a bone or other part, either closed or with a narrow opening.
  • noun A dilated vessel or canal.
  • noun (Med.) A narrow, elongated cavity, in which pus is collected; an elongated abscess with only a small orifice.
  • noun (Bot.) A depression between adjoining lobes.
  • noun (Zoöl.) See under Pallial.
  • noun (Anat.) In the lower vertebrates, a distinct chamber of the heart formed by the union of the large systematic veins and opening into the auricle.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • noun anatomy A pouch or cavity in any organ or tissue, especially the paranasal sinus.
  • noun pathology An abnormal cavity or passage such as a fistula, caused by the destruction of tissue.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • noun an abnormal passage leading from a suppurating cavity to the body surface
  • noun any of various air-filled cavities especially in the bones of the skull
  • noun a wide channel containing blood; does not have the coating of an ordinary blood vessel


from The American Heritage® Dictionary of the English Language, 4th Edition

[Middle English, hollow in the body, from Medieval Latin, from Latin, curve, hollow.]

from Wiktionary, Creative Commons Attribution/Share-Alike License

From Latin sinus.



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