'Costmary' definitions:

Definition of 'costmary'

(from WordNet)
noun
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 [syn: costmary, alecost, bible leaf, mint geranium, balsam herb, Tanacetum balsamita, Chrysanthemum balsamita]
noun
Leaves used sparingly (because of bitter overtones) in sauces and soups and stuffings

Definition of 'Costmary'

From: GCIDE
  • Costmary \Cost"ma*ry\ (k?st"m?-r?), n. [L. costum an Oriental aromatic plant (Gr. ???, cf. Ar. kost, kust) + Maria Mary. Cf. Alecost.] (Bot.) A garden plant (Chrysanthemum Balsamita) having a strong balsamic smell, and nearly allied to tansy. It is used as a pot herb and salad plant and in flavoring ale and beer. Called also alecost. [1913 Webster]