Definition of pyrethrum in English:

pyrethrum

noun

  • 1An aromatic plant of the daisy family, typically having feathery foliage and brightly colored 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

    ‘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.’
    • ‘This is the area where significant cash crops are grown, including pyrethrum (a flower that produces a natural insecticide), coffee and tea.’
    • ‘In some areas, extremely fertile soils produce coffee, tea, and pyrethrum (used in making insecticides).’
    • ‘Others are synthetic versions of naturally-occurring insecticides, such as those found in the plant pyrethrum.’
    1. 1.1An insecticide made from the dried flowers of the pyrethrum plant.
      ‘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.’
      • ‘Rotenone and pyrethrum don't work, even if applied more frequently.’
      • ‘The spray does not control the adults, so you can either handpick the adults or spray them with pyrethrum insecticide.’
      • ‘It seems probable that in the future, synthetic pyrethroids will be of more interest than pyrethrum as possible delousing agents.’
      • ‘You can treat them with pyrethrum, white oil, soapy water or just squash them with your fingers.’
      • ‘Geoff reckons to use a contact spray like pyrethrum which breaks down within about 24 hours.’
      • ‘‘That's pyrethrum,’ said Niko ‘it's used as an insecticide.’’
      • ‘For body lice, use pyrethrum with piperonyl butoxide lotion over the whole body and wash off after 10 minutes.’
      • ‘Adult mosquitoes were obtained from houses within a village by resting and pyrethrum knockdown collections.’
      • ‘You can purchase concentrated pyrethrum from a nursery or the garden supply section of your supermarket.’
      • ‘A natural pyrethrum insecticide is cheaper, less harmful and just as effective as those chemical poisons to kill spiders.’

Pronunciation

pyrethrum

/pīˈrēTHrəm/ /paɪˈriθrəm/ /pīˈreTHrəm/ /paɪˈrɛθrəm/

Origin

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.