WordNet (r) 3.0 (2006):

pay off
    v 1: yield a profit or result; "His efforts finally paid off"
    2: eliminate by paying off (debts) [syn: liquidate, pay off]
    3: pay off (loans or promissory notes) [syn: redeem, pay
       off]
    4: do or give something to somebody in return; "Does she pay you
       for the work you are doing?" [syn: pay, pay off, make
       up, compensate]
    5: pay someone with influence in order to receive a favor [syn:
       buy off, pay off]
    6: take vengeance on or get even; "We'll get them!"; "That'll
       fix him good!"; "This time I got him" [syn: pay back, pay
       off, get, fix]

Moby Thesaurus II by Grady Ward, 1.0:

87 Moby Thesaurus words for "pay off":
   advantage, afford, amortize, answer, approach, avail, be gainful,
   be handy, be of use, be profitable, be worthwhile, bear away,
   bear off, benefit, bestead, bribe, bring in, buy, buy off, clear,
   compensate, corrupt, discharge, do, do the trick, drift,
   drift off course, drive, fall down, fetch away, fill the bill, fix,
   get at, get satisfaction, get to, give good returns, grease,
   grease the palm, gross, head to leeward, honor, indemnify, lift,
   liquidate, make accounts square, make amends, make leeway,
   make requital, make restitution, make retribution, net, pay,
   pay back, pay in full, pay the bill, pay the shot, pay up, profit,
   purchase, quit, reach, recompense, redeem, redress, repay, requite,
   retire, return, reward, sag, satisfy, serve, serve the purpose,
   settle, square, square accounts, strike a balance, suborn, suffice,
   take care of, take up, tamper with, tickle the palm, yaw, yaw off,
   yield, yield a profit