/ Dictionary / Index P pyrethrin: Meaning and Definition of Find definitions for: py•re•thrin Pronunciation: (pī-rē'thrin, -reth'rin), [key] — n. Chem. Also calleda viscous, water-insoluble liquid, CHO, extracted from pyrethrum flowers, used as an insecticide. Also calleda like compound, CHO, obtained and used similarly. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. pyrenocarp pyrethroid Related Content Daily Word Quiz: topography Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language