Word Origin & History
pertaining to the healing of disease, 1640s, probably shortened from therapeutical (c.1600), from Mod.L. therapeuticus "curing, healing," from Gk. therapeutikos, from therapeutes "one ministering," from therapeutein "to cure, treat," of unknown origin, related to therapon (gen. therapontos) "attendant."
Therapeutic was used from 1540s as a noun meaning "the branch of medicine concerned with treatment of disease."