The Collaborative International Dictionary of English v.0.48:

Withhold \With*hold"\, v. t. [imp. Withheld; p. p. Withheld,
   Obs. or Archaic Withholden; p. pr. & vb. n. Withholding.]
   [With again, against, back + hold.]
   [1913 Webster]
   1. To hold back; to restrain; to keep from action.
      [1913 Webster]

            Withhold, O sovereign prince, your hasty hand
            From knitting league with him.        --Spenser.
      [1913 Webster]

   2. To retain; to keep back; not to grant; as, to withhold
      assent to a proposition.
      [1913 Webster]

            Forbid who will, none shall from me withhold
            Longer thy offered good.              --Milton.
      [1913 Webster]

   3. To keep; to maintain; to retain. [Obs.]
      [1913 Webster]

            To withhold it the more easily in heart. --Chaucer.
      [1913 Webster]

WordNet (r) 3.0 (2006):

withhold
    v 1: hold back; refuse to hand over or share; "The father is
         withholding the allowance until the son cleans his room"
         [syn: withhold, keep back]
    2: retain and refrain from disbursing; of payments; "My employer
       is withholding taxes" [syn: withhold, deduct, recoup]

Moby Thesaurus II by Grady Ward, 1.0:

112 Moby Thesaurus words for "withhold":
   abstain, abstain from, arrest, avoid, begrudge, bit, bosom, bridle,
   check, classify, close the hand, conceal, conserve, constrain,
   contain, control, cool, cool off, curb, curtail, decelerate, deny,
   detain, disallow, do without, dompt, enjoin, eschew,
   file and forget, forbear, forgo, govern, grudge, guard, hinder,
   hold, hold aloof from, hold at bay, hold back, hold down,
   hold fast, hold in, hold in check, hold in leash, hold out on,
   hold up, husband, in petto, inhibit, keep, keep back,
   keep between us, keep buttoned up, keep by one, keep close,
   keep dark, keep from, keep in, keep in check, keep in ignorance,
   keep in reserve, keep in store, keep mum, keep on hand, keep out,
   keep secret, keep snug, keep under control, keep under wraps,
   lay by, lay under restraint, let alone, let go by, make no sign,
   never let on, never touch, not give away, not tell, not touch,
   pass up, play dumb, preserve, prohibit, pull, pull in, put apart,
   put aside, put by, refrain, refrain from, refuse, rein, rein in,
   reserve, restrain, retain, retard, retrench, save, save up,
   secrete, set apart, set aside, set back, set by, shun, slow down,
   snub, spare, stand aloof from, straiten, veil