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Definition of nonagon

nonagon

/ˈnɑː.nə.ɡɑːn/
non · a · gon
Plural:nonagons
•
Adjective:nonagonal
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nonagon Lexical Profile

nonagon Game Scores & Validity

• noun

1

A plane geometric figure with nine straight sides and nine angles.

Example

"Each interior angle of a regular nonagon measures exactly 140 degrees."

Synonyms
View all synonyms for nonagon

Word Nuance & Usage

While "nonagon" is the standard term in everyday English, geometers sometimes prefer "enneagon" because it uses the pure Greek prefix "ennea-" rather than the hybrid Latin-Greek construction of "nonagon."

• Nearby Words

nonaffluent
nonaggression
nonaggressive
nonagon
nonagricultural
nonalcoholic
nonaligned

Word Origin & Etymology

Coined in the 17th century from a hybrid of the Latin "nonus" (meaning "ninth") and the Ancient Greek "gonia" (meaning "angle" or "corner"), modeled after words like "hexagon" and "octagon."

Cite this Entry

Wordmom. (2026). Definition of Nonagon. In Wordmom Dictionary. Retrieved Nov 5, 2026, from https://wordmom.com/dictionary/nonagon
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