Meaning

noun someone who betrays his country by committing treason

noun a person who says one thing and does another

originFrom Middle English traitor, traitour, traytour, from Old French traïtor (French traître), from Latin trāditor. Displaced native Middle English swike from Old English swica (“traitor”), and Middle English proditour and traditour borrowed directly from Latin. The general Old English word denoting "traitor" was lǣwa or lǣwend. Doublet of traditor.

Etymology from Wiktionary, CC BY-SA 3.0