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1580s, fabled serpent, slain by Apollo near Delphi, from Latin Python, from Greek Python "serpent slain by Apollo," probably related to Pytho, the old name of Delphi, perhaps itself 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. Zoological application to large non-venomous snakes of the tropics is from 1836, originally in French.