D defs.my
Entry 1 sense Webster, 1913

Enneagon

· En·ne·a·gon · IPA /ˈɛ.niː.ə.ɡən/
01 n. A polygon or plane figure with nine sides and nine angles; a nonagon.
  1. 1.
    A polygon or plane figure with nine sides and nine angles; a nonagon.(Geom.)