A polygon with 12 sides is called a dodecagon

Explanation

A dodecagon is a polygon with twelve sides. The word dodecagon comes from the Ancient Greek δωδεκάγωνον (dōdekágōnon), "twelve-angled," a compound of δώδεκα (dōdeka), "twelve", itself from do ("two") + deka ("ten"), and γωνία (gonía), "angle."