The word "polygon" means "many angles". There are a number of words in the English language that use the word "poly", which means "many."
Examples:
Polynomial - an expression in algebra that has "many terms."
X² - 10x - 24 is an example of a polynomial.
Polyglot - a person who can speak "many languages."
If you can speak English, Spanish, and French, you're a polyglot.
Polychromatic - a term often used in photography that means "many colors."