A twenty sided, 2D figure is called an icosagon.
A 5-sided 2D shape would be a pentagon, pent, meaning 5.
Dodecagon http://en.wikipedia.org/wiki/Dodecagon
Tetrahaidecahedron
Dodecagon
Such a 2D shape is a hexagon, a six sided figure.
10 sided 2D shape is called a decagon 20 sided 2D shape is called a icosagon 30 sided 2D shape is a swimming pool 40 sided 2D shape is unknown 50 sided 2D shape is unknown 60 sided 2d shape is unknown 70 sided 2d shape is unknown 80 sided 2d shape is unknown 90 sided 2d shape is unknown 100 sided 2d shape is unknown 110 sided 2d shape is unknown 111 sided 2d shape is unknown 120 sided 2d shape is unknown 130 sided 2d shape is unknown
A hexagon is a 6-sided polygon 2D shape.
A pentagon
Hexagon
A seven sided 2D shape is a heptagon.
hexagon
Dodecagon is the name for the regular 12 sided polygon, meaning that all its side lengths and angles are the same. Not sure if there is a name for a general 12 sided 2d shape.
A 2d nine sided shape is called a nonagon.
A ten-sided 2D polygon is known as a decagon.
A twenty sided, 2D figure is called an icosagon.
A 6 sided hexagon would fit the given description.