from The American Heritage® Dictionary of the English Language, 4th Edition
- n. Either of two viscous liquid esters, C21H28O3 or C22H28O5, that are extracted from pyrethrum flowers and used as insecticides.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. Any of a number of naturally occurring insecticides extracted from the pyrethrum plant; unusual in having a cyclopropane ring.
from the GNU version of the Collaborative International Dictionary of English
- n. A substance resembling, and isomeric with, ordinary camphor, and extracted from the essential oil of feverfew; -- called also Pyrethrum camphor.
from The Century Dictionary and Cyclopedia
- n. A resinous compound found in pellitory resin from the root of Anacyclus Pyrethrum.
pyrethr(um) + -in.(American Heritage® Dictionary of the English Language, Fourth Edition)