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.
The name of an eleven sided geometric shape is a Hendecagon or endecagon.
hendecagon
hendecagon
The name of a 11 sided polygon is Hendecagon.
Hendecagon (or endecagon)
unit gon
It is a Hendecagon (or endecagon).
A nine-sided object is known as a nonagon.
An eleven-sided polygon is a hendecagon.
Two-dimensional: Pentagon Three-dimensional: Pentahedron
hendecagon Sandra Good