It is called a nonagon and/or an enneagon. They belong to the greater family of polygons.
nonagon
Because nonagon means 9 sides
Not a regular nonagon.
A nonagon has nine sides.
A nonagon
"nonagon" is not a prefix.
Nonagon.
a nonagon
A nonagon.
A nonagon is a 2D shape so you cannot make a 3D nonagon!
Only if all nine sides are the same length.