The Collaborative International Dictionary of English v.0.48:

Gar \Gar\, v. t. [Of Scand. origin. See Gear, n.]
   To cause; to make. [Obs. or Scot.] --Spenser.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Gar \Gar\, n. [Prob. AS. g[=a]r dart, spear, lance. The name is
   applied to the fish on account of its long and slender body
   and pointed head. Cf. Goad, Gore, v.] (Zool.)
   (a) Any slender marine fish of the genera Belone and
       Tylosurus. See Garfish.
   (b) The gar pike. See Alligator gar (under Alligator),
       and Gar pike.
       [1913 Webster]

   Gar pike, or Garpike (Zool.), a large, elongated ganoid
      fish of the genus Lepidosteus, of several species,
      inhabiting the lakes and rivers of temperate and tropical
      America.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Garfish \Gar"fish`\, n. [See Gar, n.] (Zool.)
   (a) A European marine fish (Belone vulgaris); -- called
       also gar, gerrick, greenback, greenbone,
       gorebill, hornfish, longnose, mackerel guide,
       sea needle, and sea pike.
   (b) One of several species of similar fishes of the genus
       Tylosurus, of which one species (T. marinus) is
       common on the Atlantic coast. T. Caribb[ae]us, a very
       large species, and T. crassus, are more southern; --
       called also needlefish. Many of the common names of the
       European garfish are also applied to the American
       species.
       [1913 Webster]

WordNet (r) 3.0 (2006):

gar
    n 1: primitive predaceous North American fish covered with hard
         scales and having long jaws with needlelike teeth [syn:
         gar, garfish, garpike, billfish, Lepisosteus
         osseus]
    2: elongate European surface-dwelling predacious fishes with
       long toothed jaws; abundant in coastal waters [syn:
       needlefish, gar, billfish]