Have you ever thought about the range of words which have a Grecian root? There are lots of such words in mathematics, like "geometry".

Some of these words have an interesting derivation. A contemporary of Pythagoras was watching a parrot playing with some twigs, once upon a time. Although birds often play with twigs and leaves and branches, this parrot, to the mathematician's amazement, actually arranged the pieces of wood into some sort of a pattern. Then, unfortunately, the bird keeled over, dead.

The mathematician was so moved that he named the shape, "Dead parrot" although -- of course -- he said it in Greek.

Which is why we call that shape a polygon.