A nine-sided object is known as a nonagon.
Octagon.
A five sided 2 dimensional object is called a pentagon.
A two-sided object is commonly referred to as a "two-sided" or "double-sided" item. An example is a coin, which has a heads side and a tails side. Another example is double-sided tape, which has adhesive on both sides.
nonagon
A triangular pyramid.
The name of a 9 sided polygon is Nonagon.
The name of a 9 sided polygon is nonagon or enneagon.
octagon
hendecagon
Decagon.
Octagon.
the Greeks used prefexes up to ten, modernly we have sdded dodecagon for a twelvesided object and undecagon for an eleven sided object so the propor name would be a 27 sided object.
A hexakaidecagon (hexadecagon).
Decagon
A five sided 2 dimensional object is called a pentagon.
Nonagon is the name of a 9 sided shape. The US Steel Tower in Pittsburgh, Pennsylvania is a nonagon.
HEXADECAHEDRON is the correct name for a 16 sided 3D object