Sig'moid or Sig-moid'al, a.

a. [Fr. sigmoïde, Gr. σιγμοειδής, from σίγμα, sigma, and εἶδος, form, likeness.] Curved in two directions, like the letter S, or the Greek ς. Bigelow.

Sigmoid flexure (Anat.), the last curve of the colon, before it terminates in the rectum.