ˈsīnəs noun
( -es )
Etymology: New Latin, from Latin, curve, fold, hollow, bay; probably akin to Albanian ǵiri bosom, lap, Serbian zao šijati to bend
: cavity , hollow , recess : as
a. : a narrow elongated cavity or tract which extends from a focus of suppuration or other inflammatory softening to a free surface and through which pus discharges
a tuberculous sinus leading to the skin surface from a tuberculous bone or abscess
— compare fistula 2
b. : a cavity, recess, or depression that forms part of an animal body:
(1) : a cavity in the substance of a bone of the skull that usually communicates with the nostrils and contains air
the frontal sinus
(2) : one of the broad channels the outer coats of which are formed by the dura mater and which conduct blood from the brain
(3) : one of the spaces among the muscles and viscera of various invertebrates through which blood returns to the heart
(4) : a dilatation in a canal or vessel (as at the commencement of the internal jugular vein)
(5) : pallial sinus
(6) : a moderately deep indentation in the outer lip of the aperture of a univalve shell (as of a member of the genus Scissurella ) that is progressively filled in as the shell grows and forms a distinct band
c.
(1) archaic : a hole in the earth
(2) : a bay of the sea
the deep sinus of the Norwegian trench — A.H.W.Robinson
d. : a cleft or indentation between adjoining lobes (as of a leaf or corolla)
e. : the folds of the drapery of a toga covering the left arm and serving as a pocket