The Collaborative International Dictionary of English v.0.48:

Patronage \Pa"tron*age\, n. [F. patronage. Cf. LL. patronaticum,
   and L. patronatus.]
   1. Special countenance or support; favor, encouragement, or
      aid, afforded to a person or a work; as, the patronage of
      letters; patronage given to an author.
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   2. Business custom. [Commercial Cant]
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   3. Guardianship, as of a saint; tutelary care. --Addison.
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   4. The right of nomination to political office; also, the
      offices, contracts, honors, etc., which a public officer
      may bestow by favor.
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   5. (Eng. Law) The right of presentation to church or
      ecclesiastical benefice; advowson. --Blackstone.
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The Collaborative International Dictionary of English v.0.48:

Patronage \Pa"tron*age\, v. t.
   To act as a patron of; to maintain; to defend. [Obs.] --Shak.
   [1913 Webster]

WordNet (r) 3.0 (2006):

patronage
    n 1: the act of providing approval and support; "his vigorous
         backing of the conservatives got him in trouble with
         progressives" [syn: backing, backup, championship,
         patronage]
    2: customers collectively; "they have an upper class clientele"
       [syn: clientele, patronage, business]
    3: a communication that indicates lack of respect by patronizing
       the recipient [syn: condescension, disdain, patronage]
    4: (politics) granting favors or giving contracts or making
       appointments to office in return for political support
    5: the business given to a commercial establishment by its
       customers; "even before noon there was a considerable
       patronage" [syn: trade, patronage]
    v 1: support by being a patron of
    2: be a regular customer or client of; "We patronize this
       store"; "Our sponsor kept our art studio going for as long as
       he could" [syn: patronize, patronise, patronage,
       support, keep going]