tansy

noun, plural tan·sies.

1. any of several composite plants of the genus Tanacetum, especially a strong-scented, weedy, Old World herb, T. vulgare, having flat-topped clusters of tubular yellow flowers.

noun plural -sies

1. any of numerous plants of the genus Tanacetum, esp T. vulgare, having yellow flowers in flat-topped clusters and formerly used in medicine and for seasoning: family Asteraceae (composites)
2. any of various similar plants

n.(Tanacetum vulgare), mid-13c., from Old French tanesie (13c.), from Gallo-Romance *tanaceta, from Late Latin tanacetum “wormwood,” from shortened form of Greek athanasia “immortality,” so called probably for its persistence. English folklore associates it with pregnancy, either as an aid to contraception or to provoke miscarriage.