undecagon

[ uhn-dek-uh-gon, -guh n ]
/ ʌnˈdɛk əˌgɒn, -gən /

noun

a polygon having 11 angles and 11 sides.

Origin of undecagon

1720–30; < Latin un-, as in undecim eleven ( ūn(us) one + -decim, combining form of decem ten) + decagon

British Dictionary definitions for undecagon

undecagon
/ (ʌnˈdɛkəˌɡɒn) /

noun

a polygon having eleven sides

Word Origin for undecagon

C18: from Latin undecim eleven (from unus one + decem ten) + -gon