Noun
A substance resembling, and isomeric with, ordinary camphor, and extracted from the essential oil of feverfew; -- called also Pyrethrum camphor.
Source: Webster's dictionaryMany vets do not recommend the use of flea collars or flea spray on Greyhounds if it is a pyrethrin -based product. Source: Internet
Pyrethroid pesticides They were developed as a synthetic version of the naturally occurring pesticide pyrethrin, which is found in chrysanthemums. Source: Internet
Since then, pyrethrin compounds have become the dominant insecticide. Source: Internet