Definitions

from The American Heritage® Dictionary of the English Language, 5th Edition.

  • noun A topical insecticide, C21H20CL2O3, used to treat head lice and nits, scabies, and various species of ticks.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • noun A synthetic insecticide, C21H20Cl2O3, used to treat head lice, nits, scabies, and in flea collars.

Etymologies

from The American Heritage® Dictionary of the English Language, 4th Edition

[per– + (res)methrin, a pyrethroid (resm-, of unknown origin + (pyr)ethrin).]

Examples

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