Source : Webster's Revised Unabridged Dictionary (1913)

Pythagoreanism \Pyth`a*go"re*an*ism\, n.
   The doctrines of Pythagoras or the Pythagoreans.

         As a philosophic school Pythagoreanism became extinct
         in Greece about the middle of the 4th century [B. C.].
                                                  --Encyc. Brit.