What is "polygon"

In geometry, a polygon is a flat figure bounded by a closed polygonal line: for example, the hexagon is a six-sided polygon.

The word "polygon" comes from the Greek and means many (Poly) and angles (Gon).

The definition used by Euclid for polygon was a figure bounded by straight lines, these lines should be more than four, and figure any region of the plane surrounded by one or more edges.

Source: Polygon - Wikipedia