The Collaborative International Dictionary of English v.0.48:

Gulp \Gulp\, n.
   1. The act of taking a large mouthful; a swallow, or as much
      as is awallowed at once.
      [1913 Webster]

   2. A disgorging. [Colloq.]
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

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.
   [1913 Webster]

         He does not swallow, but he gulps it down. --Cowper.
   [1913 Webster]

         The old man . . . glibly gulped down the whole
         narrative.                               --Fielding.
   [1913 Webster]

   To gulp up, to throw up from the stomach; to disgorge.
      [1913 Webster]

WordNet (r) 3.0 (2006):

gulp
    n 1: a large and hurried swallow; "he finished it at a single
         gulp" [syn: gulp, draft, draught, swig]
    2: a spasmodic reflex of the throat made as if in swallowing
       [syn: gulp, gulping]
    v 1: to swallow hurriedly or greedily or in one draught; "The
         men gulped down their beers" [syn: gulp, 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"