aptychus

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noun

A hard calcareous plate forming part of the body of an ammonite.

OriginAncient Greek πτυχή →
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Meanings

nounaptychus (plural aptychi)

plural aptychi

  1. biologyA hard calcareous plate forming part of the body of an ammonite.

    It wasn't until the 1970s that paleontologists had amassed enough evidence to be certain that aptychi were modified lower jaws.

    2017, Danna Staaf, Squid Empire, ForeEdge, →ISBN, page 95

Origin

  1. Ancient Greekπτυχή“fold, layer”
  2. Englishaptychus

Modern Latin, from a- + Ancient Greek πτυχή (ptukhḗ, “fold, layer”).

More words from Ancient Greek

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Cite this entry
APA

aptychus. (n.d.). In WatkinsX Dictionary. Retrieved November 3, 2026, from https://dictionary.watkinsx.com/word/aptychus

MLA

“aptychus.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/aptychus. Accessed November 3, 2026.

Chicago

WatkinsX Dictionary, s.v. “aptychus,” accessed November 3, 2026, https://dictionary.watkinsx.com/word/aptychus.

Source: aptychus on Wiktionary, CC BY-SA 4.0.