- An organophosphorous compound used as an insecticide and veterinary ectoparasiticide; considered to be less toxic than parathion.
* * *mal·a·thi·on .mal-ə-'thī-ən, -.än n a thiophosphate insecticide C10H19O6PS2 with a lower mammalian toxicity than parathion
* * *n.an organophosphorous insecticide used to treat head and pubic lice and scabies. It is applied externally in the form of a lotion; possible side-effects are skin irritation and allergic reactions. Trade names: Derbac-M, Prioderm, Suleo-M.
* * *mal·a·thi·on (mal″ə-thiґon) an organophosphorus insecticide and topical parasiticide.
Medical dictionary. 2011.