early 15c., from Latin carminat- (past participle stem of carminare "to card," from carmen, genitive carminis, "a card for wool or flax," which is related to carrere "to card;" see card (v.2)) + -ive. As a noun from 1670s.
A medical term from the old theory of humours. The object of carminatives is to expel wind, but the theory was that they dilute and relax the gross humours from whence the wind arises, combing them out like knots in wool. [Hensleigh Wedgwood, "A Dictionary of English Etymology," 1859-65]
carminative car·min·a·tive (kär-mĭn'ə-tĭv, kär'mə-nā'-)
Inducing the expulsion of gas from the stomach and intestines. n.
A drug or agent that induces the expulsion of gas from the stomach or intestines.