WordNet (r) 3.0 (2006):

hold back
    v 1: hold back, as of a danger or an enemy; check the expansion
         or influence of; "Arrest the downward trend"; "Check the
         growth of communism in South East Asia"; "Contain the rebel
         movement"; "Turn back the tide of communism" [syn: check,
         turn back, arrest, stop, contain, hold back]
    2: keep under control; keep in check; "suppress a smile"; "Keep
       your temper"; "keep your cool" [syn: restrain, keep,
       keep back, hold back]
    3: refrain from doing; "she forbore a snicker" [syn: forbear,
       hold back]
    4: wait before acting; "the scientists held off announcing their
       results until they repeated the experiment" [syn: wait,
       hold off, hold back]
    5: secure and keep for possible future use or application; "The
       landlord retained the security deposit"; "I reserve the right
       to disagree" [syn: retain, hold, keep back, hold
       back]
    6: hold back; keep from being perceived by others; "She conceals
       her anger well" [syn: conceal, hold back, hold in]

Moby Thesaurus II by Grady Ward, 1.0:

151 Moby Thesaurus words for "hold back":
   abstain, abstain from, arrest, avoid, avoid excess, backpedal,
   backwater, begrudge, bit, block, bottle up, brake, bridle, check,
   clip the wings, close the hand, confine, conserve, constrain,
   contain, control, cool, cool off, countercheck, curb, curtail,
   dam up, damp, dampen, decelerate, delay, deny, detain,
   dispense with, do without, dompt, drag, draw rein, ease off,
   ease up, eat sparingly, eat to live, enjoin, eschew,
   exercise self-control, forbear, forgo, govern, grudge, guard,
   hinder, hold, hold aloof from, hold at bay, hold down, hold fast,
   hold in, hold in check, hold in leash, hold off, hold out on,
   hold up, husband, impede, inhibit, intercept, interfere,
   intermeddle, interrupt, intervene, keep, keep back, keep by one,
   keep from, keep in, keep in check, keep in hand, keep in reserve,
   keep in store, keep on hand, keep out, keep under control,
   keep within bounds, keep within compass, keep within limits, lag,
   lay by, lay under restraint, let alone, let down, let go by,
   let up, live plainly, lose ground, lose momentum, lose speed,
   make late, meddle, moderate, mortify the flesh, never touch,
   not touch, not use, obstruct, oppose, pass up, preserve, prohibit,
   pull, pull in, put apart, put aside, put by, reef, refrain,
   refrain from, rein, rein in, relax, repress, reserve, resist,
   restrain, retain, retard, retrench, save, save up, scotch,
   set apart, set aside, set back, set by, shun, slack off, slack up,
   slacken, slow, slow down, slow up, snub, spare, stand aloof from,
   stay, stop, straiten, suppress, take in sail, throttle down, waive,
   withhold