'Sigmoid' definitions:

Definition of 'sigmoid'

From: WordNet
adjective
Curved in two directions (like the letter S)
adjective
Of or relating to the sigmoid flexure in the large intestine [syn: sigmoid, sigmoidal]

Definition of 'Sigmoid'

From: GCIDE
  • Sigmoid \Sig"moid\, Sigmoidal \Sig*moid"al\, a. [Gr. ???; ??? sigma + e'i^dos form, likeness: cf. F. sigmo["i]de.] Curved in two directions, like the letter S, or the Greek [sigmat]. [1913 Webster]
  • 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. [1913 Webster]