Is it ensure, insure, or assure?
Old English wiht "living being, creature," from Proto-Germanic *wekhtiz (cf. Old Saxon wiht "thing, demon," Dutch wicht "a little child," Old High German wiht "thing, creature, demon," German Wicht "creature, infant," Old Norse vettr "thing, creature," Swedish vätte "spirit of the earth, gnome," Gothic waihts "something"). The only apparent cognate outside Germanic is Old Church Slavonic vešti "a thing." Not related to the Isle of Wight, which is from Latin Vectis (c.150), originally Celtic, possibly meaning "place of the division."