The Collaborative International Dictionary of English v.0.48:

Gape \Gape\, n.
   1. The act of gaping; a yawn. --Addison.
      [1913 Webster]

   2. (Zool.) The width of the mouth when opened, as of birds,
      fishes, etc.
      [1913 Webster]

   The gapes.
      (a) A fit of yawning.
      (b) A disease of young poultry and other birds, attended
          with much gaping. It is caused by a parasitic nematode
          worm (Syngamus trachealis), in the windpipe, which
          obstructs the breathing. See Gapeworm.
          [1913 Webster]

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):

gape
    n 1: an expression of openmouthed astonishment
    2: a stare of amazement (usually with the mouth open)
    v 1: look with amazement; look stupidly [syn: goggle, gape,
         gawp, gawk]
    2: be wide open; "the deep gaping canyon" [syn: gape, yawn,
       yaw]

Moby Thesaurus II by Grady Ward, 1.0:

160 Moby Thesaurus words for "gape":
   abysm, abyss, aperture, arroyo, attend, be amazed, be astonished,
   be curious, bedroom eyes, bore, box canyon, breach, break,
   broaching, burn with curiosity, canyon, cavity, chap, chasm, check,
   chimney, chink, clearing, cleft, cleuch, clough, col,
   come-hither look, coulee, couloir, crack, crane, crane the neck,
   cranny, crevasse, crevice, cut, cwm, defile, dehisce, dehiscence,
   dell, dig around for, dig up, dike, disclosure, ditch, donga, draw,
   evil eye, excavation, eye, fault, fenestra, fissure, fistula, flaw,
   flume, fontanel, foramen, fracture, furrow, gap, gaping, gash, gat,
   gaup, gawk, gaze, gaze open-mouthed, glad eye, glare, gloat,
   glower, glowering look, goggle, gorge, groove, gulch, gulf, gully,
   hang open, hiatus, hole, hollow, incision, inlet, inquire,
   interrogate, interval, joint, kloof, lacuna, laying open, leak,
   look, look at, look on, malocchio, marvel, moat, nose around for,
   nose out, notch, nullah, ogle, opening, opening up, orifice,
   oscitancy, oscitate, oscitation, outlet, pandiculation, part, pass,
   passage, passageway, peer, penetrating look, pore, query, question,
   quiz, ravine, rent, rift, rime, rubber, rubberneck, rupture,
   scissure, seam, seek, slit, slot, space, split, stand aghast,
   stand on tiptoe, stare, stare at, stare down, stare hard,
   stare openmouthed, stoma, take in, the gapes, throwing open,
   trench, uncorking, unstopping, valley, void, wadi, want to know,
   watch, yaw, yawn, yawning