Is it ensure, insure, or assure?
Old English sealf "healing ointment," from West Germanic *salbo- "oily substance" (cf. Old Saxon salba, Middle Dutch salve, Dutch zalf, Old High German salba, German salbe "ointment"), from PIE *solpa-, from root *selp- "fat, butter" (cf. Greek elpos "fat, oil," Sanskrit sarpis "melted butter"). The figurative sense of "something to soothe wounded pride, etc." is from 1736.
Old English sealfian "anoint (a wound) with salve," from Proto-Germanic *salbojanan (cf. Dutch zalven, German salben, Gothic salbon "to anoint"), from the root of salve (n.). Figurative use from c.1200. Related: Salved; salving.
"to save from loss at sea," 1706, back-formation from salvage (n.) or salvable. Related: Salved; salving.
salve (sāv, säv)
An analgesic or medicinal ointment.