sigmoid

adjective

sig·​moid ˈsig-ˌmȯid How to pronounce sigmoid (audio)
variants or less commonly sigmoidal
1
a
: curved like the letter C
b
: curved in two directions like the letter S
2
: of, relating to, or being the sigmoid colon
sigmoidally adverb

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The shape sense of sigmoid is most often used in scientific contexts to describe an s-shaped curve on a graph. Usually, though, sigmoid is used in contexts relating to the sigmoid colon-the contracted and crooked part of the colon immediately above the rectum. Sigmoid comes from sigma, the name of the 18th letter of the Greek alphabet. At one time sigma had a common form that was shaped like the Roman letter C (hence sense 1a), but sigma is equivalent to the English letter S (hence sense 1b).

Examples of sigmoid in a Sentence

Recent Examples on the Web The procedure was necessary to address a diverticular stenosis, or abnormal narrowing, of the sigmoid portion of the colon, said Matteo Bruni, a Holy See spokesman. Harold Maass, The Week, 5 July 2021 Francis had developed a diverticular stenosis, or narrowing, of the sigmoid portion of the large intestine. BostonGlobe.com, 6 July 2021

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'sigmoid.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

Etymology

Greek sigmoeidēs, from sigma; from a common form of sigma shaped like the Roman letter C

First Known Use

1670, in the meaning defined at sense 1a

Time Traveler
The first known use of sigmoid was in 1670

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Cite this Entry

“Sigmoid.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/sigmoid. Accessed 18 Apr. 2024.

Medical Definition

sigmoid

1 of 2 adjective
sig·​moid ˈsig-ˌmȯid How to pronounce sigmoid (audio)
1
a
: curved like the letter C
b
: curved in two directions like the letter S
2
: of, relating to, or being the sigmoid colon of the intestine
sigmoid lesions

sigmoid

2 of 2 noun
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