·noun Any fly resembling a Culex in form or habits; ·esp., in America, a small biting fly of the genus Simulium and allies, as the buffalo gnat, the black fly, ·etc.
II. Gnat ·noun A blood-sucking dipterous fly, of the genus Culex, undergoing a metamorphosis in water. The females have a proboscis armed with needlelike organs for penetrating the skin of animals. These are wanting in the males. In America they are generally called mosquitoes. ·see Mosquito.