Meaning of Pythagorean theorem

Pythag'ore'an the'orem

Pronunciation: [key]
— Geom. Geom.
  1. the theorem that the square of the hypotenuse of a right triangle is equal to the sum of the squares of the other two sides.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.