Source : Webster's Revised Unabridged Dictionary (1913)

Stagger \Stag"ger\, v. i. [imp. & p. p. {Staggered}; 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.

            Deep was the wound; he staggered with the blow.
                                                  --Dryden.

   2. To cease to stand firm; to begin to give way; to fail.
      ``The enemy staggers.'' --Addison.

   3. To begin to doubt and waver in purposes; to become less
      confident or determined; to hesitate.

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

Source : WordNet®

staggering
     adj 1: walking unsteadily; "a stqaggering gait" [syn: {lurching}, {stumbling},
             {weaving}]
     2: so surprisingly impressive as to stun or overwhelm; "such an
        enormous response was astonishing"; "an astounding
        achievement"; "the amount of money required was
        staggering"; "suffered a staggering defeat"; "the figure
        inside the boucle dress was stupefying" [syn: {astonishing},
         {astounding}, {stupefying}]