• synonyms


[pahy-ree-thruh m, -reth-ruh m]
  1. any of several chrysanthemums, as Chrysanthemum coccineum, having finely divided leaves and showy red, pink, lilac, or white flowers, cultivated as an ornamental.
  2. any of several chrysanthemums, as C. cinerariifolium, or C. coccineum, cultivated as a source of insecticides.
  3. Pharmacology. the dried flower heads of these plants, used chiefly as an insecticide and sometimes in medicine for certain skin disorders.
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Origin of pyrethrum

1555–65; < Latin: pellitory < Greek pýrethron, akin to pyretós fever; compare pellitory
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for pyrethrum

Historical Examples

  • Sialagogues, as mercury internally, and pyrethrum externally.

    Zoonomia, Vol. II

    Erasmus Darwin

  • Previous experience with pyrethrum was not very satisfactory.

    Insects and Diseases

    Rennie W. Doane

  • After the plants begin to head, pyrethrum or salt water may be used.

  • How anything can be gay with Pyrethrum uliginosum I cannot imagine.

  • Pyrethrum or buhach may be used in similar manner, and kerosene emulsion has been highly recommended by some experimenters.

British Dictionary definitions for pyrethrum


  1. any of several cultivated Eurasian chrysanthemums, such as Chrysanthemum coccineum and C. roseum, with white, pink, red, or purple flowers
  2. any insecticide prepared from the dried flowers of any of these plants, esp C. roseum
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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 Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012