[¦tü ə′mē·nō ¦fīv ‚nī·trō′thī·ə‚zōl] (pharmacology) C3H3N3O2S A fluffy, greenish to orange-yellow powder with a slightly bitter taste; decomposes at 202°C; used as a veterinary drug in turkeys and chickens for histomonads and for trichomoniasis in pigeons.