What does Boxing Day have to do with boxing?
Old English (Northumbrian) fryhto, metathesis of fyrhtu "fear, dread, trembling, horrible sight," from Proto-Germanic *furkhtaz "afraid" (cf. Old Saxon forhta, Old Frisian fruchte, Old High German forhta, German Furcht, Gothic faurhtei "fear"). Not etymologically related to the word fear, which superseded it 13c. as the principal word except in cases of sudden terror. For spelling evolution, see fight.