Source : Webster's Revised Unabridged Dictionary (1913)

Gnat \Gnat\, n. [AS. gn[ae]t.]
   1. (Zo["o]l.) 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}.

   2. 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.

   {Gnat catcher} (Zo["o]l.), one of several species of small
      American singing birds, of the genus {Polioptila}, allied
      to the kinglets.

   {Gnat flower}, the bee flower.

   {Gnat hawk} (Zo["o]l.), the European goatsucker; -- called
      also {gnat owl}.

   {Gnat snapper} (Zo["o]l.), a bird that catches gnats.

   {Gnat strainer}, a person ostentatiously punctilious about
      trifles. Cf. --Matt. xxiii. 24.