Sig"moid (?), Sig*moid"al (?), a. [Gr. ; sigma + form, likeness: cf. F. sigmoide.]
Curved in two directions, like the letter S, or the Greek &sigmat;.
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.
© Webster 1913.