pyrethrum
- n made of dried flower heads of pyrethrum plants
- n white-flowered pyrethrum of Balkan area whose pinnate leaves are white and silky-hairy below; source of an insecticide; sometimes placed in genus Chrysanthemum
- n 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
- n used in former classifications for plants later placed in genus Chrysanthemum and now often included in genus Tanacetum
- The biggest human setback has been loss of pyrethrum, far away the deadliest prewar insecticide, of which almost the entire supply came from Japan.
- They should contain both DDT and pyrethrum (or some similar toxicant).
- Pan American Airways conscientiously sprays its Pacific Clippers with a pyrethrum extract at each stop.