[ non-uh-gon, -guh n ]
/ ˈnɒn əˌgɒn, -gən /


a polygon having nine angles and nine sides.


Origin of nonagon

1680–90; < Latin nōn(us) ninth + -a- (extracted from pentagon, hexagon, etc.) + -gon
Also called enneagon.

Related forms

non·ag·o·nal [non-ag-uh-nl] /nɒnˈæg ə nl/, adjective Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for nonagon

  • There is said to be only one triangle, only one nonagon, and only one of diamond shape in all the forty thousand.

    One Irish Summer|William Eleroy Curtis

British Dictionary definitions for nonagon


/ (ˈnɒnəˌɡɒn) /


a polygon having nine sidesAlso called: enneagon

Derived Forms

nonagonal (nɒnˈæɡənəl), adjective
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012