/puy ree"thrin, -reth"rin/ , n. Chem.
1. Also called pyrethrin I . a viscous, water-insoluble liquid, C 21 H 28 O 3 , extracted from pyrethrum flowers, used as an insecticide.
2. Also called pyrethrin II . a like compound, C 22 H 28 O 5 , obtained and used similarly.
[ 1830-40; PYRETHR(UM) + -IN 2 ]