sinus Meaning, Definition & Usage

noun an abnormal passage leading from a suppurating cavity to the body surface
fistula.
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
venous sinus.

L., a bent surface, a curve, the folds or bosom of a garment, etc., a bay. Cf. Sine, n.

plural L Sinus, E Sinuses

An opening; a hollow; a bending.
A bay of the sea; a recess in the shore.
(Anat. & Zoöl.) A cavity; a depression. Specifically: (a) A cavity in a bone or other part, either closed or with a narrow opening. (b) A dilated vessel or canal.
(Med.) A narrow, elongated cavity, in which pus is collected; an elongated abscess with only a small orifice.
(Bot.) A depression between adjoining lobes. ✍ A sinus may be rounded, as in the leaf of the white oak, or acute, as in that of the red maple.