If you wish to communicate information, I suggest you call it an 200-gon. Although there is a prefix for 200 (dihecta-) I suggest you keep it simple. Not only is the use of long Greek prefices pretentious, you will only annoy the reader who will probably have to consult a dictionary. Having said that, if you do want to be pretentious or obfuscate, you can use the link below for polygons with up to 999 sides. http://faculty.kutztown.edu/schaeffe/Tutorials/General/Polygons.html
it is called a seven sided shape in Canada
An five sided shape is called a Pentagon
A 128-sided shape is called a hecatoicosioctagon.
a 69 sided shape is called a sexagon
A 90 sided shape is called Enneacontagon.
A 200 sided shape is called a dictogon
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200-gon.
it is called a seven sided shape in Canada
a one sided shape is called a henagon and a 2 sided shape is called a digon
A 10-sided shape is called a decagon.
An five sided shape is called a Pentagon
A 150 sided shape is called heptaconta.
Hommasquabblelagagon
The 22 sided shape is called a: ICOSIKAIDIGON
A five-sided shape is called a pentagon.
A 128-sided shape is called a hecatoicosioctagon.