From Middle English theft, thefte, þefte, þefþe, þiefþe, Old English þīefþ, from Proto-West Germanic *þiubiþu, from Proto-Germanic *þiubiþō, from *þeubaz (“thief”), equivalent to thief or thieve + -t (abstract nominal suffix). Cognate with Old Frisian thiuvethe, thiufthe (“theft”), dialectal Dutch diefte (“theft”), obsolete German Diebde (“theft”), Icelandic þýfð (“theft”).