[pahy-ree-thruh m, -reth-ruh m]
- 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
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Examples from the Web for pyrethrum
Sialagogues, as mercury internally, and pyrethrum externally.Zoonomia, Vol. II</p>
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.The Practical Garden-Book
C. E. Hunn
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.Asparagus, its culture for home use and for market:
F. M. Hexamer
- 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
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