pyrethrin

American  

[pahy-ree-thrin, -reth-rin] / paɪˈri θrɪn, -ˈrɛθ rɪn /

noun

Chemistry.

1. Also called pyrethrin I.  a viscous, water-insoluble liquid, C 2 1 H 2 8 O 3 , extracted from pyrethrum flowers, used as an insecticide.

2. Also called pyrethrin II.  a like compound, C 2 2 H 2 8 O 5 , obtained and used similarly.

---

pyrethrin British  

/ paɪˈriːθrɪn /

noun

1. Also called: pyrethrin I.  an oily water-insoluble compound used as an insecticide. Formula: C 21 H 28 O 3

2. Also called: pyrethrin II.  a compound of similar chemical structure and action, also found in pyrethrum. Formula: C 22 H 28 O 5

---

Etymology

Origin of pyrethrin

First recorded in 1830–40; pyrethr(um) + -in ²

Compare meaning

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

• pyrethrum vs. pyrethrin

Example Sentences

The team also used chemical analysis to determine how two of pyrethrum’s molecular components—EBF and pyrethrin—elicit the repellent response.

From Scientific American

Although each product has the same effect on insects — and presents the same risks to beneficial insects — pyrethrin usually is more potent and lasts longer.

From Washington Post

It’s the naturally derived form of pyrethrin, which, like boric acid, is deadly to insects, but has very low toxicity to humans and other mammals.

From Washington Post

Pyrethrum is extracted from chrysanthemum flowers; pyrethrin is created in a lab.

From Washington Post

Pyrethrin and its synthetic derivatives are used in garden insecticides, pet sprays, mosquito repellents and lice shampoos.

From New York Times