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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