"tending to calm or soothe," early 15c., from Medieval Latin sedativus "calming, allaying," from sedat-, past participle stem of sedare, causative of sedere "to sit" (see sedentary). The noun derivative meaning "a sedative drug" is attested from 1785. Hence, "whatever soothes or allays."[sedative etymology, sedative origin, 英语词源]