Is it ensure, insure, or assure?
Old English hwilc (West Saxon) "which," short for hwi-lic "of what form," from Proto-Germanic *khwilikaz (cf. Old Saxon hwilik, Old Norse hvelikr, Swedish vilken, Old Frisian hwelik, Middle Dutch wilk, Dutch welk, Old High German hwelich, German welch, Gothic hvileiks "which"), from *khwi- "who" (see who) + *likan "body, form" (cf. Old English lic "body;" see like (adj.)). In Middle English used as a relative pronoun where Modern English would use who, as still in the Lord's Prayer. Old English also had parallel forms hwelc and hwylc, which disappeared 15c.
Money; the NEEDFUL (1833+)