In geometry, a nonagon (/ˈnɒnəɡɒn/) or enneagon (/ˈɛniəɡɒn/) is a nine-sided polygon or 9-gon.

What is a nine sided shape called?

The word nonagon comes from the Latin word "nona", meaning nine, and "gon", meaning sides. So it literally means "nine sided shape". Nonagons are also called enneagon, which comes from the Greek word "enneagonon", which means "nine corners".

Are polygons a shape?

A polygon is a flat, two-dimensional (2D) shape with straight sides that is fully closed (all the sides are joined up). The sides must be straight. Polygons may have any number of sides. A shape with curved sides is not a polygon.