The Collaborative International Dictionary of English v.0.48:

Gape \Gape\ (g[aum]p; in Eng, commonly g[=a]p; 277), v. i. [imp.
   & p. p. Gaped (g[aum]pt or g[=a]pt); p. pr. & vb. n.
   Gaping] [OE. gapen, AS. geapan to open; akin to D. gapen to
   gape, G. gaffen, Icel. & Sw. gapa, Dan. gabe; cf. Skr. jabh
   to snap at, open the mouth. Cf. Gaby, Gap.]
   1. To open the mouth wide; as:
      (a) Expressing a desire for food; as, young birds gape.
          --Dryden.
      (b) Indicating sleepiness or indifference; to yawn.
          [1913 Webster]

                She stretches, gapes, unglues her eyes,
                And asks if it be time to rise.   --Swift.
          [1913 Webster]
      (c) Showing unselfconsciousness in surprise, astonishment,
          expectation, etc.
          [1913 Webster]

                With gaping wonderment had stared aghast.
                                                  --Byron.
      (d) Manifesting a desire to injure, devour, or overcome.
          [1913 Webster]

                They have gaped upon me with their mouth. --Job
                                                  xvi. 10.
          [1913 Webster]

   2. To open or part widely; to exhibit a gap, fissure, or
      hiatus.
      [1913 Webster]

            May that ground gape and swallow me alive! --Shak.
      [1913 Webster]

   3. To long, wait eagerly, or cry aloud for something; -- with
      for, after, or at.
      [1913 Webster]

            The hungry grave for her due tribute gapes.
                                                  --Denham.

   Syn: To gaze; stare; yawn. See Gaze.
        [1913 Webster]

WordNet (r) 3.0 (2006):

gaping
    adj 1: with the mouth wide open as in wonder or awe; "the gaping
           audience"; "we stood there agape with wonder"; "with
           mouth agape" [syn: agape(p), gaping]

Moby Thesaurus II by Grady Ward, 1.0:

117 Moby Thesaurus words for "gaping":
   abysmal, abyssal, agape, aghast, agog, ajar, all agog, amazed,
   anticipant, anticipating, anticipative, anticipatory, astonished,
   astounded, at gaze, awaiting, awed, awestruck, beguiled,
   bewildered, bewitched, bottomless, breathless, captivated,
   cavernous, certain, chinky, cleft, cloven, confident, confounded,
   cracked, cut, deep as hell, dehiscence, dehiscent, dumbfounded,
   dumbstruck, eager, enchanted, enraptured, enravished, enthralled,
   entranced, expectant, expecting, fascinated, fathomless, fissured,
   fissury, flabbergasted, forearmed, forestalling, forewarned, gape,
   gappy, gauping, gazing, hopeful, hypnotized, in anticipation,
   in awe, in awe of, in expectation, looking for, looking forward to,
   lost in wonder, marveling, mesmerized, not surprised, open-eyed,
   openmouthed, optimistic, oscitancy, oscitant, oscitation,
   overwhelmed, pandiculation, plumbless, plunging, popeyed, prepared,
   puzzled, rapt in wonder, ready, rent, rift, rimose, rimulose,
   ringent, sanguine, slack-jawed, slit, soundless, spellbound, split,
   staggered, staring, stupefied, sure, surprised, the gapes,
   thunderstruck, under a charm, unfathomable, unfathomed, unsounded,
   unsurprised, waiting, waiting for, watching for, wide-eyed,
   without bottom, wonder-struck, wondering, yawn, yawning