ETYM Latin costum an Oriental aromatic plant (cf. Arabic kost, kust) + Maria Mary. Related to Alecost.
1. Leaves used sparingly (because of bitter overtones) in sauces and soups and stuffings.
2. Tansy-scented Eurasian perennial herb with buttonlike yellow flowers; used as potherb or salad green and sometimes for potpourri or tea or flavoring; sometimes placed in genus Chrysanthemum.