per·​meth·​rin (ˌ)pər-ˈme-thrən How to pronounce permethrin (audio)
: a synthetic pyrethroid C21H20Cl2O3 used especially as an insecticide

Example Sentences

Recent Examples on the Web Imidacloprid, permethrin, and pyriproxyfen Advecta 3 Topical Treatment for Dogs is designed to kill ticks and fleas on contact. Amber Smith, Discover Magazine, 23 Oct. 2022 The tubes are filled with fluffy material laced with permethrin. T. Edward Nickens, Field & Stream, 13 July 2020 Chang suggests applying permethrin 1 percent lotion or other pyrethrin-containing topical agents. Bill Sullivan, Discover Magazine, 5 June 2021 One effective way to treat lice is to use a shampoo containing an insecticide like permethrin. Bill Sullivan, Discover Magazine, 8 Jan. 2021 Treatment options span the range from manually picking out the lice with specialized combs to shampoos containing the substances permethrin or pyrethrin, which act to kill the lice by paralyzing them. Nina Shapiro, Forbes, 4 Oct. 2022 Do not use permethrin products directly on skin, though. Hannah Kirby, Journal Sentinel, 30 Aug. 2022 Another great way to protect yourself is to treat your clothing, socks, and shoes with permethrin. Cindy Kuzma, SELF, 10 Aug. 2022 Most products are in the 20 to 30% range, which is safe for most users (though, more potent chemical like permethrin use much less). Ryan Wichelns, Popular Mechanics, 30 June 2022 See More

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'permethrin.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Word History


per- + methyl + pyrethrin

First Known Use

1975, in the meaning defined above

Time Traveler
The first known use of permethrin was in 1975

Dictionary Entries Near permethrin

Cite this Entry

“Permethrin.” Dictionary, Merriam-Webster, Accessed 25 Mar. 2023.

Medical Definition


per·​meth·​rin pər-ˈmeth-rən How to pronounce permethrin (audio)
: a synthetic pyrethroid pesticide C21H20Cl2O3 used especially against insects, ticks, and mites

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