Two-dimensional: Pentagon
Three-dimensional: Pentahedron
The name of an eleven sided geometric shape is a Hendecagon or endecagon.
hendecagon
hendecagon
It is a Hendecagon (or endecagon).
An 11 sided polygon is an undecagon
It is an undecagon which has 11 sides. Eleven sided shapes are usually called hendecagons, which uses the greek for eleven - Hendeka and corner -gon. However they can also be termed as undecagons or unidecagons.
The name for a 57 sided shape is derived by combining the name for a 50 sided shape with the name for a 7 sided shape. A 57 sided shape is called a pentacontaheptagon.
The name of a 11 sided polygon is Hendecagon.
An 11-sided shape is called a hendecagon or undecagon. In Greek, 'hendeka-' has the meaning of eleven and '-gon' means corner. The word hendecagon is derived from these two Greek words.
A 14 sided shape is called a Tetradecagon.
a twelve sided shape is called a dodecagon.
A million sided shape is called a Megagon.