'pyrethrum' definitions:

Definition of 'pyrethrum'

(from WordNet)
noun
Made of dried flower heads of pyrethrum plants
noun
White-flowered pyrethrum of Balkan area whose pinnate leaves are white and silky-hairy below; source of an insecticide; sometimes placed in genus Chrysanthemum [syn: pyrethrum, Dalmatian pyrethrum, Dalmatia pyrethrum, Tanacetum cinerariifolium, Chrysanthemum cinerariifolium]
noun
Spring-flowering garden perennial of Asiatic origin having finely divided aromatic leaves and white to pink-purple flowers; source of an insecticide; sometimes placed in genus Chrysanthemum [syn: painted daisy, pyrethrum, Tanacetum coccineum, Chrysanthemum coccineum]
noun
Used in former classifications for plants later placed in genus Chrysanthemum and now often included in genus Tanacetum [syn: Pyrethrum, genus Pyrethrum]