noun ·Rare ·Advanced level

Definitions

Noun

1. 1
   A polygon with 18 sides and 18 vertices. rare

   "A regular octadecagon cannot be constructed using a compass and straightedge."

Synonyms

All synonyms

18-gon

Example

More examples

"A regular octadecagon cannot be constructed using a compass and straightedge."

Etymology

From octadeca- + -gon.

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Data sourced from Wiktionary, WordNet, CMU, and other open linguistic databases. Updated March 2026.