pyrethrum
/ˌpaɪˈriːθrəm/noun
1- an aromatic plant of the daisy family, typically having feathery foliage and brightly coloured flowers除虫菊。
1.1
- Genus Tanacetum (formerly Chrysanthemum or Pyrethrum), family Compositae: several species, in particular T. coccineum, grown as an ornamental, and T. cinerariifolium, grown as a source of the insecticide pyrethrum.艾菊属（原名茼蒿属或匹菊属）, 菊科：数种, 尤指作为观赏植物种植的红花除虫菊和作为除虫菊杀虫剂原料种植的除虫菊。
1.2
- mass noun an insecticide made from the dried flowers of these plants除虫菊杀虫剂。
词源
Middle English (denoting pellitory)： from Latin, from Greek purethron 'feverfew'. The current senses (based on the former genus name) date from the late 19th cent.