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.
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.
Source: Webster's dictionaryGirls blush, sometimes, because they are alive, half wishing they were dead to save the shame. The sudden blush devours them, neck and brow; They have drawn too near the fire of life, like gnats, and flare up bodily, wings and all. What then? Who's sorry for a gnat or girl? Elizabeth Barrett Browning
I think we have the attention span of a gnat. You know, with cell phones and Twitter. Jeff Daniels
You could see the flames and the outer skin of the spacecraft glowing; and burning, baseball-size chunks flying off behind us. It was an eerie feeling, like being a gnat inside a blowtorch flame. William Anders
Despise not the weak: the gnat stings the eyes of the lion. Latin Proverb
The great elephant of India cares not for a gnat. Latin Proverb
The gnat trusting itself to the flame is singed. Latin Proverb