Is it ensure, insure, or assure?
c.1200, "cure for a disease or disorder; means of counteracting an evil," from Anglo-French remedie, Old French remede "remedy, cure" (12c., Modern French remède) and directly from Latin remedium "a cure, remedy, medicine, antidote, that which restores health," from re-, intensive prefix (or perhaps literally, "again;" see re-), + mederi "to heal" (see medical (adj.)). Figurative use from c.1300.
c.1400, from Old French remedier or directly from Latin remediare, from remedium (see remedy (n.)). Related: Remedied; remedying.
remedy rem·e·dy (rěm'ĭ-dē)
Something, such as medicine or therapy, that relieves pain, cures disease, or corrects a disorder. v. rem·e·died, rem·e·dy·ing, rem·e·dies
To relieve or cure a disease or disorder.