Etymology

sigmoid

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Today it means: Semi-circular, like the uncial or lunate sigma (similar to English C). Full definition →

Ancient Greek σῑγμοειδής (sīgmoeidḗs) ← Proto-Hellenic *wéidos ← Proto-Indo-European *wéydos
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The story

  1. Ancient Greekσῖγμᾰ (sîgmă)
  2. Proto-Indo-European*weyd-
  3. Proto-Indo-European*wéydos
  4. Proto-Hellenic*wéidos
  5. Ancient Greekεἶδος (eîdos)
  6. Ancient Greekσῑγμοειδής (sīgmoeidḗs)
  7. English todaysigmoid

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.

Etymology from Wiktionary, CC BY-SA 4.0.