pyrethrum

American  

[pahy-ree-thruhm, -reth-ruhm] / paɪˈri θrəm, -ˈrɛθ rəm /

noun

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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pyrethrum British  

/ paɪˈriːθrəm /

noun

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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Etymology

Origin of pyrethrum

First recorded in 1555–65; from Latin, from Greek pýrethron, the name of the flower, akin to pyretós “fever”

Compare meaning

How does pyrethrum compare to similar and commonly confused words? Explore the most common comparisons:

• pyrethrum vs. pyrethrin

Example Sentences

A new study in Nature Communications finally shows how pyrethrum works, with two components acting synergistically to deter the pesky bloodsuckers.

From Scientific American • Aug. 18, 2021

Dong and her colleagues next plan to investigate the neural circuits behind the repellency induced by pyrethrum and similar natural substances.

From Scientific American • Aug. 18, 2021

The Documentary category was won by Vito Fusco, of Italy, for his series on Kenya's pyrethrum flowers, which are used as a natural insecticide.

From BBC • Apr. 15, 2021

"During the 1980s, the pyrethrum crisis began, instigated by the chemical synthesis of pyrethroids that led to the manufacturing of cheaper but non-organic products," he said.

From BBC • Apr. 15, 2021

If he does not edge them with blue lobelia, he edges them with some yellow stuff which I think he calls pyrethrum.

From The New Gulliver and Other Stories by Pain, Barry