Pythia (n.)

1580s, name of a fabled serpent, slain by Apollo near Delphi, from Latin Python, from Greek Pythōn "serpent slain by Apollo," probably related to Pythō, the old name of Delphi. Chaucer has it (late 14c.) as Phitoun.

This might be related to pythein "to rot," or from PIE *dhubh-(o)n-, from *dheub- "hollow, deep, bottom, depths," and used in reference to the monsters who inhabit them. Loosely used for "any very large snake," hence the zoological application to large non-venomous snakes of the tropics (1836, originally in French). Related: Pythonic.

c. 1600, "pertaining to Delphi or Delphic Apollo," from Pythia + -an. As a noun from 1590s. The Pythian Games were one of the four great national festivals of ancient Greece, held every four years at Delphi in honor of Apollo.