The Collaborative International Dictionary of English v.0.48:

Collector \Col*lect"or\, n. [LL. collector one who collects: cf.
   F. collecteur.]
   1. One who collects things which are separate; esp., one who
      makes a business or practice of collecting works of art,
      objects in natural history, etc.; as, a collector of
      coins.
      [1913 Webster]

            I digress into Soho to explore a bookstall. Methinks
            I have been thirty years a collector. --Lamb.
      [1913 Webster]

   2. A compiler of books; one who collects scattered passages
      and puts them together in one book.
      [1913 Webster]

            Volumes without the collector's own reflections.
                                                  --Addison.
      [1913 Webster]

   3. (Com.) An officer appointed and commissioned to collect
      and receive customs, duties, taxes, or toll.
      [1913 Webster]

            A great part of this is now embezzled . . . by
            collectors, and other officers.       --Sir W.
                                                  Temple.
      [1913 Webster]

   4. One authorized to collect debts.
      [1913 Webster]

   5. A bachelor of arts in Oxford, formerly appointed to
      superintend some scholastic proceedings in Lent. --Todd.
      [1913 Webster]

WordNet (r) 3.0 (2006):

collector
    n 1: a person who collects things [syn: collector,
         aggregator]
    2: a person who is employed to collect payments (as for rent or
       taxes) [syn: collector, gatherer, accumulator]
    3: a crater that has collected cosmic material hitting the earth
    4: the electrode in a transistor through which a primary flow of
       carriers leaves the region between the electrodes

Moby Thesaurus II by Grady Ward, 1.0:

114 Moby Thesaurus words for "collector":
   accumulator, addict, admirer, amateur, arbiter,
   arbiter elegantiarum, arbiter of taste, aspirant, aspirer,
   authority, base, beg, beglerbeg, bey, bill collector, bon vivant,
   booster, buff, bug, burgrave, candidate, cognoscente,
   collection agent, connaisseur, connoisseur, coveter, critic, demon,
   desirer, devotee, dey, dilettante, douanier, dunner, eager beaver,
   emitter, energumen, enthusiast, eparch, epicure, epicurean, exarch,
   exciseman, expert, faddist, fan, fanatic, fancier, farmer, fiend,
   filamentary transistor, follower, freak, gatherer, gauleiter,
   germanium crystal triode, good judge, gourmand, gourmet, governor,
   governor-general, great one for, groupie, hankerer, hobbyist,
   hook-collector transistor, hopeful, hound, idolater, idolizer,
   infatuate, judge, khedive, lieutenant governor, lover, magpie,
   maven, miser, nabob, nawab, nut, pack rat, palatine,
   point-contact transistor, proconsul, provincial, pursuer,
   refined palate, rhapsodist, rooter, satrap, solicitant, spacistor,
   stadtholder, subahdar, sucker for, suitor, tax collector, tetrarch,
   tetrode transistor, transistor, unipolar transistor, vali,
   vice-king, viceroy, virtuoso, visionary, votary, wali, wanter,
   wisher, worshiper, yearner, zealot



Bouvier's Law Dictionary, Revised 6th Ed (1856):

COLLECTOR, officer. One appointed to receive taxes or other impositions; as
collector of taxes; collector of militia fines, &c. A collector is also a
person appointed by a private person to collect the credits due him. Metc. &
Perk. Dig. h.t.