therapeutic (adj.)
pertaining to the healing of disease, 1640s, from Modern Latin therapeuticus "curing, healing," from Greek therapeutikos, from therapeutein "to cure, treat medically," primarily "do service, take care of, provide for," of unknown origin, related to therapon "attendant." Therapeutic was used from 1540s as a noun meaning "the branch of medicine concerned with treatment of disease." Related: Therapeutical (c.1600).