costmary

Etymology

Latin costum, from Ancient Greek κόστος (kóstos, “an Oriental aromatic plant”), and Maria (“the Virgin Mary”).

noun

1. An aromatic plant (Tanacetum balsamita), once used to flavour ale (prior to use of hops); also used as a bookmark in Bibles and other holy texts to dissuade silverfish and other pests.
   The Marigolde, and cherefull Rosemarie; / The Spartan Mirtle, whence sweet gumb does flowe; / The purple Hyacinths, and fresh Costmarie, / And Saffron, sought for in Cilician soyle 1591, “Virgils Gnat”, in Edmund Spenser, transl., Complaints, translation of Culex by Virgil