# sigmoid

> English word · Adjective · IPA /ˈsɪɡ.mɔɪd/ · frequency rank #90,991

## Definitions
1. Semi-circular, like the uncial or lunate sigma (similar to English C).
2. Curved in two directions, like the letter "S", or the Greek ς (sigma); having a serpentine shape.
3. Curved in two directions, like the letter "S", or the Greek ς (sigma); having a serpentine shape.
4. Relating to the sigmoid colon.

## Etymology
Borrowing from Ancient Greek σῑγμοειδής (sīgmoeidḗs, “of the shape of sigma”), from σῖγμᾰ (sîgmă, “sigma”) + -ο- (-o-) + -ειδής (-eidḗs, “-oid, -like”); Equivalent to sigma + -oid. Compare with French sigmoïde.

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-05-06.
Canonical page: https://plainspell.com/en/word/sigmoid