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[pahy-ree-thruh m, -reth-ruh m] /paɪˈri θrəm, -ˈrɛθ rəm/
any of several chrysanthemums, as Chrysanthemum coccineum, having finely divided leaves and showy red, pink, lilac, or white flowers, cultivated as an ornamental.
any of several chrysanthemums, as C. cinerariifolium, or C. coccineum, cultivated as a source of insecticides.
Pharmacology. the dried flower heads of these plants, used chiefly as an insecticide and sometimes in medicine for certain skin disorders.
Origin of pyrethrum
1555-65; < Latin: pellitory < Greek pýrethron, akin to pyretós fever; compare pellitory Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for pyrethrum
  • For example, pyrethrum is a pesticide approved for both plant and animal production.
  • Adult mosquitoes are controlled with pyrethrum or organophosphate based products.
  • pyrethrum is a naturally occurring mixture of chemicals found in certain chrysanthemum flowers.
British Dictionary definitions for pyrethrum


any of several cultivated Eurasian chrysanthemums, such as Chrysanthemum coccineum and C. roseum, with white, pink, red, or purple flowers
any insecticide prepared from the dried flowers of any of these plants, esp C. roseum
Word Origin
C16: via Latin from Greek purethron feverfew, probably from puretos fever; see pyretic
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
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