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.
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   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.
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   3. pl. Bewilderment; perplexity. [R.] --Shak.
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   Stomach staggers (Far.), distention of the stomach with
      food or gas, resulting in indigestion, frequently in
      death.
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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.
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            Deep was the wound; he staggered with the blow.
                                                  --Dryden.
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   2. To cease to stand firm; to begin to give way; to fail.
      "The enemy staggers." --Addison.
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   3. To begin to doubt and waver in purpose; to become less
      confident or determined; to hesitate.
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            He [Abraham] staggered not at the promise of God
            through unbelief.                     --Rom. iv. 20.
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The Collaborative International Dictionary of English v.0.48:

Stagger \Stag"ger\, v. t.
   1. To cause to reel or totter.
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            That hand shall burn in never-quenching fire
            That staggers thus my person.         --Shak.
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   2. To cause to doubt and waver; to make to hesitate; to make
      less steady or confident; to shock.
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            Whosoever will read the story of this war will find
            himself much staggered.               --Howell.
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            Grants to the house of Russell were so enormous, as
            not only to outrage economy, but even to stagger
            credibility.                          --Burke.
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   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.
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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"