The Collaborative International Dictionary of English v.0.48:

Whack \Whack\, n.
   1. A smart resounding blow. [Colloq.]
      [1913 Webster]

   2. A portion; share; allowance. [Slang]
      [Webster 1913 Suppl.]

   3. an attempt; as, to take a whack at it. [Colloq.]
      [PJC]

   Out of whack, out of order. [Slang]
      [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

out of whack
    adj 1: out of balance or out of adjustment; "the front wheel of
           my bicycle is out of whack"

Moby Thesaurus II by Grady Ward, 1.0:

93 Moby Thesaurus words for "out of whack":
   amiss, antagonistic, antipathetic, askew, at cross-purposes,
   at loggerheads, at odds, at variance, at war, awry, broken,
   clashing, cockeyed, contradictory, contrary, convulsed, cranky,
   cross, deranged, differing, disaccordant, disagreeable,
   disagreeing, disarranged, discomfited, discomposed, disconcerted,
   discordant, discrepant, disharmonious, dislocated, disordered,
   disorderly, disorganized, disproportionate, dissident, dissonant,
   disturbed, divergent, functionless, grating, haywire, hostile,
   immiscible, in condition, in disorder, in disrepair, in order,
   in repair, inaccordant, inapplicable, incompatible, inharmonious,
   inoperable, inoperative, jangling, jarring, misplaced, negative,
   nonfunctional, nonutilitarian, on the blink, on the fritz, otiose,
   out of accord, out of commission, out of condition, out of gear,
   out of joint, out of kelter, out of kilter, out of order,
   out of place, out of repair, out of tune, perturbed, repugnant,
   roily, shuffled, turbid, turbulent, unconducive, uncongenial,
   unemployable, unfit, unharmonious, unhelpful, unsettled,
   unsuitable, unusable, unworkable, upset, variant