[1] : The Collaborative International Dictionary of English v.0.48

whack \whack\, v. i.
   to strike anything with a smart blow.
   1913 webster

   to whack away, to continue striking heavy blows; as, to
      whack away at a log. colloq.
      1913 webster
see also:
to whack away 

[2] : 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.
see also:
out of whack 

[3] : The Collaborative International Dictionary of English v.0.48

whack \whack\, v. t. imp.  p. p. whacked; p. pr.  vb. n.
   whacking. cf. thwack.
   1. to strike; to beat; to give a heavy or resounding blow to;
      to thrash; to make with whacks. colloq.
      1913 webster

            rodsmen were whackingtheir way through willow
            brakes.                               --g. w. cable.
      1913 webster

   2. to divide into shares; as, to whack the spoils of a
      robbery; -- often with up. slang
      webster 1913 suppl.
see also:
whacked whacking thwack 

[4] : WordNet (r) 2.0

whack
     n 1: the sound made by a sharp swift blow
     2: the act of hitting vigorously; "he gave the table a whack"
        syn: knock, belt, rap, whang
     v : hit hard; "the teacher whacked the boy" syn: wham, whop,
          wallop
see also:
knock belt rap whang wham whop 
wallop 

[5] : Moby Thesaurus II by Grady Ward, 1.0

129 moby thesaurus words for "whack":
   approach, assay, attempt, bang, bash, bat, beating, belt, bid,
   biff, blow, bonk, bout, box, box the ears, buffet, bump, burst,
   bust, catch, chance, chop, clap, clash, clip, clobber, clout,
   clump, coldcock, crack, crash, crump, cuff, cut, dash, deal,
   deal a blow, deck, dig, ding, dint, drub, drubbing, drumming,
   effort, endeavor, essay, experiment, fetch, fetch a blow, flap,
   fling, flop, fusillade, gambit, go, hit, hit a clip, inning,
   innings, jab, knock, knock cold, knock down, knock out,
   let have it, lick, move, offer, opportunity, paste, pelt, place,
   plunk, poke, pop, pound, punch, rap, relief, report, round, say,
   shot, slam, slap, slap the face, slat, slog, slug, smack, smash,
   smite, snap, soak, sock, spell, splat, stab, stagger, step, strike,
   strike at, stroke, strong bid, swap, swat, swing, swipe, tap,
   tattoo, tentative, thump, thwack, time, time at bat,
   token punishment, trial, trial and error, try, turn, undertaking,
   wallop, wham, whap, whirl, whomp, whop, yerk

[6] : Jargon File (4.3.1, 29 Jun 2001)

whack v. according to arch-hacker james gosling designer of news,
   gosmacs and java, to "...modify a program with no idea whatsoever how
   it works." see whacker. it is actually possible to do this in
   nontrivial circumstances if the change is small and well-defined and you
   are very good at glarking things from context. as a trivial example,
   it is relatively easy to change all `stderr' writes to `stdout' writes
   in a piece of c filter code which remains otherwise mysterious.


see also:
news gosmacs whacker glark 

[7] : The Free On-line Dictionary of Computing (27 SEP 03)

whack
     
        according to arch-hacker james gosling, to "...modify a
        program with no idea whatsoever how it works." see
        whacker.  it is actually possible to do this in nontrivial
        circumstances if the change is small and well-defined and you
        are very good at glarking things from context.  as a trivial
        example, it is relatively easy to change all "stderr" writes
        to "stdout" writes in a piece of c filter code which remains
        otherwise mysterious.
     
        jargon file
     
     
see also:
whacker glark jargon file 

Whack >> W Words
Whack, definition of term: Whack
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Out Of Whack >> O Words
Out Of Whack, definition of term: Out Of Whack
out+of+whack_pag1.html