-ative

"quieting excessive action," by 1831, from French calmatif; see calm (adj.) + -ative. A Greek-Latin hybrid; purists prefer sedative, but OED writes that "The Latinic suffix is here defensible on the ground of It. and Sp. calmar, F. calmer ...." Also as a noun, "a quieting drug" (1847).

1640s, from fix (v.) + -ative, suffix meaning "of or related to; tending to." As a noun, from 1870, "that which fixes."