Definition of pyrethrum in English:

Share this entry


Pronunciation: /pʌɪˈriːθrəm/


1An aromatic plant of the daisy family, typically having feathery foliage and brightly coloured flowers.
  • 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.
Example sentences
  • Not all herbs smell good - catmint, curry plant, pyrethrum, rue, santolina and tansy are all pretty pongy.
  • Some are derived from plants, such as pyrethrum and neem.
  • When I looked closely I could see the truck had a PyGanic label with the iconic pyrethrum flower on the side.
1.1 [mass noun] An insecticide made from the dried flowers of pyrethrum plants.
Example sentences
  • By the mid 1800s, the heads of chrysanthemum flowers were used to obtain pyrethrum, and rotenone was extracted from the derris plant.
  • Pesticides that are approved for organic farming include copper, sulfur, petroleum distillates, and pyrethrum.
  • Daisy plants were first used centuries ago as a lice remedy in the Middle East, and this led to the discovery of pyrethrum insecticides.


Middle English (denoting pellitory): from Latin, from Greek purethron 'feverfew'. The current senses (based on the former genus name) date from the late 19th century.

For editors and proofreaders

Line breaks: pyr|eth¦rum

Share this entry

What do you find interesting about this word or phrase?

Comments that don't adhere to our Community Guidelines may be moderated or removed.