• synonyms


  1. shaped like the letter C.
  2. shaped like the letter S.
  3. of, relating to, or situated near the sigmoid flexure of the large intestine.
Show More
Sometimes sig·moi·dal [sig-moi-dl] /sɪgˈmɔɪ dl/.

Origin of sigmoid

First recorded in 1660–70, sigmoid is from the Greek word sigmoeidḗs shaped like a sigma. See sigma, -oid
Related formssig·moi·dal·ly, adverbpost·sig·moid, adjectivepost·sig·moi·dal, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for sigmoidal

Historical Examples

  • A sigmoidal fold, showing a bed xx in an overfold with arch (a), trough (t) and common limb c.

    The Principles of Stratigraphical Geology

    J. E. Marr

British Dictionary definitions for sigmoidal


adjective Also: sigmoidal
  1. shaped like the letter S
  2. of or relating to the sigmoid colon of the large intestine
Show More
  1. See sigmoid colon
Show More

Word Origin

C17: from Greek sigmoeidēs sigma-shaped
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for sigmoidal



"shaped like a C" (1660s) or "shaped like an S" (1786), from sigma (q.v.) + -oid. Especially of the flexure of the colon (1891).

Show More
Online Etymology Dictionary, © 2010 Douglas Harper

sigmoidal in Medicine


  1. Having the shape of the letter S.
  2. Of or relating to the sigmoid flexure of the colon.
Show More
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.