Well, that depends on what you mean by shape and side.
In a plane, any 2 dimensional figure that has 8 sides is an octogon. Each side is a straight line segment. It doesn't matter if the sides are all the same length or not.
If you are working in 3 dimensional space, then the answer is an octohedron. In this case, the side is a plane figure (a triangle). The regular octohedron is one of the 5 platonic solids, once thought by the ancients to comprise the fundamental building blocks of matter.
decagon
A kite and an arrow head are 2 of them
triangle.
A hexagon is an example of a regular polygon with 6 sides.
A pentagon or an irregular pentagon if the sides are unequal in length.
a quadrilateral
hexagon
decagon
An octagon.
I would call (not cal) an 8 faced shape (not shap) an octahedron.
A kite and an arrow head are 2 of them
Hexagon
triangle.
A nonagon has 9 sides
a crescent has 19 sides
A hexagon is an example of a regular polygon with 6 sides.
A pentagon or an irregular pentagon if the sides are unequal in length.