- per·meth·rin pər-'meth-rən n a synthetic pyrethroid pesticide C21H20Cl2O3 used esp. against insects, ticks, and mites
* * *n.a synthetic derivative of the naturally occurring insecticide pyrethrin that is applied externally to treat head lice, pubic lice, and scabies. Trade name: Lyclear.
* * *per·meth·rin (pər-methґrin) a pyrethroid insecticide applied topically in the treatment of infestations by Pediculus humanus capitis, Sarcoptes scabiei, and various species of ticks; also applied to objects such as bedding and furniture. In veterinary medicine, used in ear tags for cattle to combat biting flies and in flea collars for cats and dogs.
Medical dictionary. 2011.