noun
: either of two venous sinuses of the dura mater:
a. : one passing backward in the convex attached margin of the falx cerebri and ending at the internal occipital protuberance by fusion with the transverse sinus — called also superior sagittal sinus
b. : one lying in the posterior two thirds of the concave free margin of the falx cerebri and ending posteriorly by joining the great cerebral vein to form the straight sinus — called also inferior sagittal sinus