nicotine /nik″ətēn/ [Jean Nicot de Villemain, French ambassador to Portugal, 1530–1600] , a colorless, rapidly acting toxic substance in tobacco that is one of the major contributors to the ill effects of smoking. It is used as an insecticide in agriculture and as a parasiticide in veterinary medicine. Ingestion of large amounts causes salivation, nausea, vomiting, diarrhea, headache, vertigo, slowing of the heartbeat, and, in acute cases, paralysis of respiratory muscles.
