(pathology) An arrhythmia presumably caused by a malfunction of the sinus node, the heart's primary pacemaker.

(anatomy) Any of numerous venous channels (as the sagittal sinuses, straight sinus, and transverse sinuses) that are situated between the two layers of the dura mater, that have no valves, and that drain blood from the brain and the bones forming the cranium and empty it into the internal jugular vein.

(anatomy) The smaller of the two petrosal sinuses that is situated superiorly and connects the cavernous and transverse sinuses of the same side.

(anatomy) The larger of the two petrosal sinuses that is situated inferiorly in a sulcus on each side formed by the junction of the petrous portion of the temporal bone and the basilar portion of the occipital bone and that extends from the posterior inferior end of the cavernous sinus through the jugular foramen to join the internal jugular vein of the same side.

(anatomy) One of two venous sinuses of the dura mater lying in the posterior two thirds of the concave free inferior margin of the falx cerebri and ending posteriorly by joining the great cerebral vein to form the straight sinus.

(anatomy) One of two venous sinuses of the dura mater passing backward in the convex attached superior margin of the falx cerebri and ending at the internal occipital protuberance by fusion with the transverse sinus.

(mathematics) Having the shape or characteristics of a sine wave. / (anatomy) Relating to any of several channels (the sinusoids) through which venous blood passes in various organs.

A sine wave (or combination of such waves)

(pathology) An inflammation of one or more paranasal sinuses.

plural of sinus