nonagon
/ˈnɒnəɡ(ə)n
/noun
A plane figure with nine straight sides and nine angles.The room is shaped as a large nonagon, its sheer walls, a flat metallic grey, rising almost two stories up and curving into a dome....
- What's the perimeter of a nonagon whose sides are each twice the length of the side of a square whose area is 16 square units?
Derivatives
nonagonal
Origin
Mid 17th century: formed irregularly from Latin nonus 'ninth', on the pattern of words such as hexagon.