Source : Webster's Revised Unabridged Dictionary (1913)

Gulp \Gulp\, n.
   1. The act of taking a large mouthful; a swallow, or as much
      as is awallowed at once.

   2. A disgorging. [Colloq.]

Gulp \Gulp\, v. t. [imp. & p. p. {Gulped}; p. pr. & vb. n.
   {Gulping}.] [D. gulpen, cf. OD. golpe gulf.]
   To swallow eagerly, or in large draughts; to swallow up; to
   take down at one swallow.

         He does not swallow, but he gulps it down. --Cowper.

         The old man . . . glibly gulped down the whole
         narrative.                               --Fielding.

   {To gulp up}, to throw up from the stomach; to disgorge.

Source : WordNet®

gulp
     n 1: a large and hurried swallow; "he finished it at a single
          gulp" [syn: {draft}, {draught}, {swig}]
     2: a spasmodic reflex of the throat made as if in swallowing
        [syn: {gulping}]
     v 1: to swallow hurriedly or greedily or in one draught; "The men
          gulped down their beers" [syn: {quaff}, {swig}]
     2: utter or make a noise, as when swallowing too quickly; "He
        gulped for help after choking on a big piece of meat"