The names of the sided shapes as mentioned above are as follows:
A 17 sided shape is called a heptadecagon or a heptakaidecagon. This is part of the polygon shapes.- 17 sided shape
- 18 sided shape
An 18 sided shape is called an octadecagon (octa meaning 8 and decagon meaning 10)
- 19 sided shape
A 19 sided shape is called an enneadecagon (pronounced en-ee-deck-uh-gon)
- 20 sided shape
A 20 sided shape is called an icsoagon.
All of these shapes are from the polygon family. A polygon simply means that it is a shape that is bounded by a closed path or circuit, which is made up of a sequence of straight lines or edges. Each polygon is named after the amount of sides it has as seen above.
Other examples of this are:
A 30 sided shape is called a triocontagon
A 100 sided shape is called a hectogon
A 1000 sided shaped is called a chilliagon
These polygons are named right up to a million sided shape which is called a megagon and an apeirogon which is a degenerate polygon with infinite sides.
A lot of the names of the shapes are derived from Greek including the word polygon itself which translated means many corners or angles.