The Collaborative International Dictionary of English v.0.48:

Perquisite \Per"qui*site\, n. [L. perquisitum, fr. perquisitus,
   p. p. of perquirere to ask for diligently; per + quaerere to
   seek. See Per-, and Quest.]
   1. Something gained from a place or employment over and above
      the ordinary salary or fixed wages for services rendered;
      -- examples are, a fee allowed by law to an officer for a
      specific service; the use of a company automobile or other
      company property.

   Syn: perk.
        [1913 Webster + PJC]

              The pillage of a place taken by storm was regarded
              as the perquisite of the soldiers.  --Prescott.
        [1913 Webster]

              The best perquisites of a place are the advantages
              it gaves a man of doing good.       --Addison.
        [1913 Webster]

   2. pl. (Law) Things gotten by a man's own industry, or
      purchased with his own money, as opposed to things which
      come to him by descent. --Mozley & W.
      [1913 Webster]

WordNet (r) 3.0 (2006):

perquisite
    n 1: an incidental benefit awarded for certain types of
         employment (especially if it is regarded as a right); "a
         limousine is one of the fringe benefits of the job" [syn:
         fringe benefit, perquisite, perk]
    2: a right reserved exclusively by a particular person or group
       (especially a hereditary or official right); "suffrage was
       the prerogative of white adult males" [syn: prerogative,
       privilege, perquisite, exclusive right]

Moby Thesaurus II by Grady Ward, 1.0:

107 Moby Thesaurus words for "perquisite":
   Trinkgeld, accessories, appanages, appendages, appointments,
   appurtenances, belongings, blackmail, bonus, bonus system, boodle,
   booty, bounty, bribe, capital gains, choses, choses in action,
   choses in possession, choses local, choses transitory, cleanup,
   clear profit, consideration, dividends, donative, double time,
   earnings, fee, filthy lucre, fringe benefit, gain, gains, get,
   gettings, gleanings, graft, gratuity, gravy, grease, gross,
   gross profit, haul, hoard, honorarium, hot goods, incentive pay,
   income, inducement, interest, killing, lagniappe, largess,
   liberality, loot, lucre, makings, material things, movables,
   neat profit, net, net profit, overtime pay, palm oil,
   paper profits, paraphernalia, pelf, percentage, perk, perks,
   perquisites, personal effects, pickings, plunder, pork barrel,
   pourboire, premium, prize, proceeds, profit, profits, public till,
   public trough, rake-off, receipts, return, returns, salve,
   solatium, something extra, spoil, spoils, spoils of office,
   sportula, squeeze, stealings, stolen goods, store, swag, sweetener,
   take, take-in, things, till, tip, trappings, wealth, winnings