WordNet (r) 3.0 (2006):

write off
    v 1: concede the loss or worthlessness of something or somebody;
         "write it off as a loss"
    2: write something fluently, and without hesitation
    3: cancel (a debt)
    4: reduce the estimated value of something; "For tax purposes
       you can write off the laser printer" [syn: expense, write
       off, write down]

Moby Thesaurus II by Grady Ward, 1.0:

126 Moby Thesaurus words for "write off":
   abate, abatement, abolish, abolishment, abolition, abrogate,
   abrogation, absolve, agio, allow, allowance, annul, annulment,
   bank discount, bate, belittle, breakage, bury the hatchet, cancel,
   canceling, cancellation, cash discount, cassation, chain discount,
   charge off, charge to experience, charge-off, concession,
   countermand, counterorder, cut, declare a moratorium, decry,
   deduct, deduction, defeasance, depreciate, depreciation, derogate,
   detract from, devaluate, devalue, disannul, discount, disparage,
   do away with, downgrade, drawback, forget, forgive and forget,
   grace period, invalidate, invalidation, kick back, kickback,
   let it go, let it pass, lower, make allowance, make void,
   mark down, minimize, moratorium, nullification, nullify,
   obliterate, obliteration, override, overrule, penalty,
   penalty clause, percentage, premium, price reduction, price-cut,
   rebate, rebatement, recall, recant, recantation, reduce, reduction,
   refund, renege, repeal, rescind, rescinding, rescindment,
   rescission, retract, retraction, reversal, reverse, revocation,
   revoke, revokement, rollback, run down, salvage, set aside, setoff,
   setting aside, suspend, suspension, take a premium, take off, tare,
   time discount, trade discount, tret, underrate, underselling,
   undervalue, vacate, vacation, vacatur, void, voidance, voiding,
   waive, waiver, waiving, wipe out, withdraw, withdrawal,
   write down