{ Sig″moid (?), Sig‐moid″al (?), } a. [Gr. ���; ��� sigma + ��� form, likeness: cf. F. sigmoïde.] Curved in two directions, like the letter S, or the Greek ς.
Sigmoid flexure(Anat.), the last curve of the colon before it terminates in the rectum. See Illust. under Digestive. — Sigmoid valves. (Anat.) See Semilunar valves, under Semilunar.