Definitions

from The American Heritage® Dictionary of the English Language, 5th Edition.

  • adjective Having the shape of the letter S.
  • adjective Of or relating to the sigmoid colon.

from The Century Dictionary.

  • Shaped like the Greek capital letter sigma in either of its forms. (See sigma, 1.)
  • Specifically— Of the colon, at the end of the descending colon, terminating ill the rectum.
  • Of the spinal column of man and a few of the highest apes, highly characteristic of the erect attitude. It does not exist in the infant.
  • Of the cervical vertebral of birds and some reptiles, as cryptodirous turtles, when the head is drawn in straight upon the shoulders. It disappears when the head is thrust forward and the neck thus straightened out. It is very strongly marked in long-necked buds, as herons.
  • Synonyms See semilunar.
  • noun A sigmoid curve.
  • noun The region of the sigmoid flexure of the colon.

from the GNU version of the Collaborative International Dictionary of English.

  • adjective Curved in two directions, like the letter S, or the Greek ς.
  • adjective (Anat.) the last curve of the colon before it terminates in the rectum. See Illust. under Digestive.
  • adjective (Anat.) See Semilunar valves, under Semilunar.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • adjective geometry Curved in two directions, like the letter "S", or the Greek ς (sigma).
  • adjective geometry, archaic Semi-circular, like the lunar sigma (similar to English C).
  • adjective anatomy Relating to the sigmoid flexure of the large intestine.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • adjective of or relating to the sigmoid flexure in the large intestine
  • adjective curved in two directions (like the letter S)

Etymologies

from The American Heritage® Dictionary of the English Language, 4th Edition

[Greek sīgmoeidēs : sīgma, sigma; see sigma + -oeidēs, -oid.]

from Wiktionary, Creative Commons Attribution/Share-Alike License

From Ancient Greek σιγμοειδής (sigmoeidēs), from σίγμα (sigma) or σῖγμα (sigma, "sigma") + εἶδος (eidos, "form, likeness"). Compare with French sigmoïde.

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Examples

Comments

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  • Some corrections are needed for (spell-check defeating) typos for the definitions listed for 'sigmoid' in the section attributed to The Century Dictionary:

    1. The sigmoid colon could feasibly end 'in' or 'at' the rectum but not 'ill' the rectum.

    2. 'Of the cervical vertebral' should be change to 'vertebrae'.

    3. Herons are not small protuberances developing on stems of plants; 'buds'. Herons belong to a class of warm blooded, egg laying, winged, feathered, beaked vertebrates; 'birds'.


    Additionally, in the second definition for 'sigmoid' attributed to Wiktionary, the term for the Greek symbol for Sigma in the form of a semicircle (found beginning in earliest manuscripts of the New Testament) is 'lunate sigma', though a few non-authoritative examples using 'lunar sigma' come up in searches.

    April 24, 2020