1) Duodecagon 2) Shape 1) Polygon 2) Polygonal shape 3) Twelve-sided figure 
In geometry, a dodecagon is any polygon with twelve sides and twelve angles. ==Regular dodecagon== The perimeter for an inscribed dodecagon of radius 1 is 12√(2 - √3), or approximately 6.21165708246. The perimeter for a circumscribed dodecagon of radius 1 is 24(2 – √3), or approximately 6.43078061835. Interestingly, this is double the valu...
• (n.) A figure or polygon bounded by twelve sides and containing twelve angles.
Regular dodecagon A polygon with 12 sides.
Do·dec'a·gon noun [ Greek ... twelve + ... angle: confer French dodécagone .] (Geom.) A figure or polygon bounded by twelve sides and containing twelve angles. 
A dodecagon is a twelve-sided regular polygon.
[n] - a twelve-sided polygon
A polygon with 12 sides. Each internal angle is 150° and the sum of the internal angles is 1800°. See also: Dodecahedron, Polygon.
noun a twelve-sided polygon
a polygon having 12 angles and 12 sides.