The Collaborative International Dictionary of English v.0.48:

Patron \Pa"tron\, v. t.
   To be a patron of; to patronize; to favor. [Obs.] --Sir T.
   Browne.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Patron \Pa"tron\, a.
   Doing the duty of a patron; giving aid or protection;
   tutelary. --Dryden.
   [1913 Webster]

   Patron saint (R. C. Ch.), a saint regarded as the peculiar
      protector of a country, community, church, profession,
      etc., or of an individual.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Patron \Pa"tron\, n. [F., fr. L. patronus, fr. pater a father.
   See Paternal, and cf. Patroon, Padrone, Pattern.]
   1. One who protects, supports, or countenances; a defender.
      "Patron of my life and liberty." --Shak. "The patron of
      true holiness." --Spenser.
      [1913 Webster]

   2. (Rom. Antiq.)
      (a) A master who had freed his slave, but still retained
          some paternal rights over him.
      (b) A man of distinction under whose protection another
          person placed himself.
      (c) An advocate or pleader.
          [1913 Webster]

                Let him who works the client wrong
                Beware the patron's ire.          --Macaulay.
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   3. One who encourages or helps a person, a cause, or a work;
      a furtherer; a promoter; as, a patron of art.
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   4. (Eccl. Law) One who has gift and disposition of a
      benefice. [Eng.]
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   5. A guardian saint. -- called also patron saint.
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   6. (Naut.) See Padrone, 2.
      [1913 Webster]

   Patrons of Husbandry, the grangers. See Granger, 2.
      [1913 Webster]

WordNet (r) 3.0 (2006):

patron
    n 1: a regular customer [syn: patron, frequenter]
    2: the proprietor of an inn
    3: someone who supports or champions something [syn: patron,
       sponsor, supporter]

Moby Thesaurus II by Grady Ward, 1.0:

184 Moby Thesaurus words for "patron":
   Dionysus, Maecenas, OD, Samaritan, Santa Claus, abettor, admirer,
   advocate, aficionado, aid, aider, almoner, almsgiver, angel,
   apologist, assignor, assister, attender, audience, awarder, backer,
   befriender, benefactor, benefactress, benefiter, bestower,
   boatswain, booster, boss, buff, buyer, bwana, captain, caterer,
   champion, chandler, cheerful giver, chef, chief, chief engineer,
   chief mate, church dignitary, client, commander, commissariat,
   commissary, conferrer, consignor, contributor, customer,
   deck officer, defender, dependence, donator, donor, ecclesiarch,
   elder, employer, encourager, endorser, exponent, fairy godmother,
   fan, favorer, feoffor, financer, frequenter, friend,
   friend at court, funder, furnisher, giver, good Samaritan,
   good person, goodman, grantor, grubstaker, guarantor,
   guardian angel, guru, habitue, haunter, help, helper, helping hand,
   husband, imparter, jack-at-a-pinch, lady bountiful, liege,
   liege lord, lord, lord paramount, lover, mainstay, maintainer,
   manciple, mark, master, mate, meal ticket, merchant,
   ministering angel, ministrant, naval officer, navigating officer,
   navigator, overlord, padrone, paramount, paranymph, partisan,
   paterfamilias, patriarch, patroness, philanthropist, pillar, pipes,
   presenter, promoter, prospect, protagonist, protector, protectress,
   provider, provisioner, purchaser, purveyor, quartermaster, rabbi,
   regular, regular customer, reliance, retailer, rock, safekeeper,
   sahib, sailing master, second, second mate, seconder, sectary,
   seigneur, seignior, settler, shipmaster, sider, skipper, spectator,
   sponsor, staker, stalwart, standby, starets, steward, stock clerk,
   storekeeper, subscriber, succorer, sucker, sugar daddy, supplier,
   support, supporter, surety, sustainer, sutler, sympathizer,
   teacher, testate, testator, testatrix, the Old Man, theatergoer,
   tower, tower of strength, upholder, victualer, visitor, vivandier,
   votary, vouchsafer, watch officer, well-wisher



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

PATRON, eccl. law. He who has the disposition and gift of an ecclesiastical
benefice. In the Roman law it signified the former master of a freedman.
Dig. 2, 4, 8, 1.