| pyrethrin | <chemistry> A substance resembling, and isomeric with, ordinary camphor, and extracted from the essential oil of feverfew. Synonym: Pyrethrum camphor. Origin: NL. Pyrethrum, generic name of feverfew, Gr. Feverfew. Source: Websters Dictionary (01 Mar 1998) |
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| pyrethrine | <chemistry> An alkaloid extracted from the root of the pellitory of Spain (Anacyclus pyrethrum). Source: Websters Dictionary (01 Mar 1998) |
| pyrethrins | <chemical> The active insecticidal constituent of pyrethrum flowers. Pyrethrin I is the pyretholone ester of chrysanthemummonocarboxylic acid and pyrethrin II is the pyretholone ester of chrysanthemumdicarboxylic acid monomethyl ester. Pharmacological action: insecticide, botanical. (12 Dec 1998) |