1) Certain geometric figure 2) Defective stop sign 3) Hot tub shape, sometimes 4) Many-sided figure 5) Nine sided polygon 6) Nine-sided figure 7) Nine-sided polygon 8) Nine-sided shape 9) Nine-sider 10) Odd-shaped figure 11) Polygon 12) Polygonal shape 13) Shape of a Bahai temple 1) Enneagon 
In geometry, a nonagon n (or enneagon n) is a nine-sided polygon. The name `nonagon` is a prefix hybrid formation, from Latin (nonus, `ninth` + gonon), used equivalently, attested already in the 16th century in French nonogone and in English from the 17th century. The name `enneagon` comes from Greek enneagonon (εννεα, `nine` + γων...
• (n.) A figure or polygon having nine sides and nine angles. • (n.) A figure or polygon having nine sides and nine angles.
A polygon with 9 sides. A nonagonal number is a number of the form n(7n - 5)/2.
Non'a·gon noun [ Latin nonus ninth + Greek ... angle.] (Math.) A figure or polygon having nine sides and nine angles. 
A nonagon (or enneagon) is a nine-sided polygon.
[n] - a nine-sided polygon
nonagon, nonagonal; enneagon A polygon having nine angles and nine sides.
A nine sided polygon.
A nine sided polygon. Each internal angle is 140° and the sum of the internal angles is 1260°. See also: Polygon.
noun a nine-sided polygon
a polygon having nine angles and nine sides. Also called