pyrethrin(redirected from pyrethrin I)
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Either of two viscous liquid esters, C21H28O3 or C22H28O5, that are extracted from pyrethrum flowers and used as insecticides.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
1. (Elements & Compounds) Also called: pyrethrin I an oily water-insoluble compound used as an insecticide. Formula: C21H28O3
2. (Elements & Compounds) Also called: pyrethrin II a compound of similar chemical structure and action, also found in pyrethrum. Formula: C22H28O5
[C19: from pyrethrum + -in]
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
py•re•thrin(paɪˈri θrɪn, -ˈrɛθ rɪn)
either of two chemicals, C21H28O3 or C22H28O5, extracted from pyrethrum flowers: used as an insecticide.
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