The Collaborative International Dictionary of English v.0.48:

Stagger \Stag"ger\, n.
   1. An unsteady movement of the body in walking or standing,
      as if one were about to fall; a reeling motion; vertigo;
      -- often in the plural; as, the stagger of a drunken man.
      [1913 Webster]

   2. pl. (Far.) A disease of horses and other animals, attended
      by reeling, unsteady gait or sudden falling; as, parasitic
      staggers; apopletic or sleepy staggers.
      [1913 Webster]

   3. pl. Bewilderment; perplexity. [R.] --Shak.
      [1913 Webster]

   Stomach staggers (Far.), distention of the stomach with
      food or gas, resulting in indigestion, frequently in
      death.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Stagger \Stag"ger\ (-g[~e]r), v. i. [imp. & p. p. Staggered
   (-g[~e]rd); p. pr. & vb. n. Staggering.] [OE. stakeren,
   Icel. stakra to push, to stagger, fr. staka to punt, push,
   stagger; cf. OD. staggeren to stagger. Cf. Stake, n.]
   1. To move to one side and the other, as if about to fall, in
      standing or walking; not to stand or walk with steadiness;
      to sway; to reel or totter.
      [1913 Webster]

            Deep was the wound; he staggered with the blow.
                                                  --Dryden.
      [1913 Webster]

   2. To cease to stand firm; to begin to give way; to fail.
      "The enemy staggers." --Addison.
      [1913 Webster]

   3. To begin to doubt and waver in purpose; to become less
      confident or determined; to hesitate.
      [1913 Webster]

            He [Abraham] staggered not at the promise of God
            through unbelief.                     --Rom. iv. 20.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Stagger \Stag"ger\, v. t.
   1. To cause to reel or totter.
      [1913 Webster]

            That hand shall burn in never-quenching fire
            That staggers thus my person.         --Shak.
      [1913 Webster]

   2. To cause to doubt and waver; to make to hesitate; to make
      less steady or confident; to shock.
      [1913 Webster]

            Whosoever will read the story of this war will find
            himself much staggered.               --Howell.
      [1913 Webster]

            Grants to the house of Russell were so enormous, as
            not only to outrage economy, but even to stagger
            credibility.                          --Burke.
      [1913 Webster]

   3. To arrange (a series of parts) on each side of a median
      line alternately, as the spokes of a wheel or the rivets
      of a boiler seam.
      [1913 Webster]

WordNet (r) 3.0 (2006):

stagger
    n 1: an unsteady uneven gait [syn: lurch, stumble,
         stagger]
    v 1: walk as if unable to control one's movements; "The drunken
         man staggered into the room" [syn: stagger, reel,
         keel, lurch, swag, careen]
    2: walk with great difficulty; "He staggered along in the heavy
       snow" [syn: stagger, flounder]
    3: to arrange in a systematic order; "stagger the chairs in the
       lecture hall" [syn: stagger, distribute]
    4: astound or overwhelm, as with shock; "She was staggered with
       bills after she tried to rebuild her house following the
       earthquake"

Moby Thesaurus II by Grady Ward, 1.0:

290 Moby Thesaurus words for "stagger":
   affright, agitate, alarm, alternate, amaze, amble, amplitude,
   arrhythmia, astonish, astound, awe, awestrike, back and fill,
   barge, be drunk, be incredible, be intoxicated, be unbelievable,
   bedaze, bedazzle, bewilder, blunder, boggle, bowl along, bowl down,
   bowl over, brokenness, bundle, burden, camber, capriciousness,
   capsize, careen, career, choppiness, clump, come a cropper,
   confound, crack, crankle, curdle the blood, daze, dazzle,
   desultoriness, devastate, discombobulate, discompose, disconcert,
   disconnectedness, discontinuity, disquiet, disturb, dither, do,
   drag, droop, dumbfound, dumbfounder, ebb and flow, eccentricity,
   electrify, erraticness, fall, fall down, fall flat, fall headlong,
   fall over, fall prostrate, falter, fare, fibrillation,
   fill with doubt, fitfulness, fits and starts, flabbergast,
   flight path, floor, flounce, flounder, fluctuate, fluctuation,
   flummox, flurry, fluster, flutter, foot, footslog, fright,
   frighten, funk, fuss, gait, gallop, get, get a cropper, go,
   go through phases, halt, have two minds, hippety-hop, hitch,
   hobble, hop, horripilate, inconstancy, intermittence, irregularity,
   jar, jerkiness, jog, jolt, jump, knock over, labor, limp, list,
   lock step, lumber, lunge, lurch, make one tremble, mince,
   mincing steps, muddle through, nonplus, nonuniformity, oscillate,
   overcome, overpower, overwhelm, pace, paddle, paralyze,
   pass belief, pass out, patchiness, peg, pendulate, perplex,
   perturb, petrify, piaffe, piaffer, pitch, pitch and plunge, plod,
   plunge, pop, prance, puzzle, rack, raise apprehensions, rattle,
   rearrange, reel, ring the changes, rock, roll, roughness, ruffle,
   sashay, saunter, scare, scuff, scuffle, scuttle, see double,
   seesaw, seethe, shake, shake up, shamble, shatter, shift,
   shilly-shally, shock, shot, shuffle, sidle, single-foot,
   skin effect, skin friction, skip, slap, slink, slip, slither, slog,
   slouch, slowness, space out, spasticity, spook, sporadicity,
   sporadicness, spottiness, sprawl, spread-eagle, stab, stalk,
   stammer, stamp, startle, step, stir, stiver, stomp, straddle,
   straggle, stride, strike dead, strike dumb, strike with wonder,
   stroll, strolling gait, struggle, strut, stumble, stump, stun,
   stupefy, surprise, swagger, sway, swing, take a fall, take a flop,
   take a header, take a pratfall, take a spill, take aback, tax,
   teeter, teeter-totter, thrash about, tilt, tittup, toddle, topple,
   topple down, topple over, toss, toss and tumble, toss and turn,
   totter, traipse, tread, trip, trot, trouble, trudge, try, tumble,
   turn, turn turtle, uncertainty, unevenness, unman,
   unmethodicalness, unnerve, unpredictability, unsettle,
   unsteadiness, unstring, unsystematicness, upset, vacillate,
   variability, vary, velocity, volutation, waddle, walk, wallop,
   wallow, wamble, waver, wax and wane, weave, welter, whack, wheel,
   whiffle, whimsicality, whirl, wiggle, wobble, zag, zig, zigzag