The Collaborative International Dictionary of English v.0.48:

Commissary \Com"mis*sa*ry\, n.; pl. Commissaries. [LL.
   commissarius, fr. L. commissus, p. p. of committere to
   commit, intrust to. See Commit.]
   1. One to whom is committed some charge, duty, or office, by
      a superior power; a commissioner.
      [1913 Webster]

            Great Destiny, the Commissary of God. --Donne.
      [1913 Webster]

   2. (Eccl.) An officer of the bishop, who exercises
      ecclesiastical jurisdiction in parts of the diocese at a
      distance from the residence of the bishop. --Ayliffe.
      [1913 Webster]

   3. (Mil.)
      (a) An officer having charge of a special service; as, the
          commissary of musters.
      (b) An officer whose business is to provide food for a
          body of troops or a military post; -- officially
          called commissary of subsistence. [U. S.]
          [1913 Webster]

                Washington wrote to the President of Congress .
                . . urging the appointment of a commissary
                general, a quartermaster general, a commissary
                of musters, and a commissary of artillery. --W.
                                                  Irving
          [1913 Webster]

   Commissary general, an officer in charge of some special
      department of army service; as:
      (a) The officer in charge of the commissariat and
          transport department, or of the ordnance store
          department. [Eng.]
      (b) The commissary general of subsistence. [U. S.]

   Commissary general of subsistence (Mil. U. S.), the head of
      the subsistence department, who has charge of the purchase
      and issue of provisions for the army.
      [1913 Webster]

WordNet (r) 3.0 (2006):

commissary
    n 1: a retail store that sells equipment and provisions (usually
         to military personnel)
    2: a snack bar in a film studio

Moby Thesaurus II by Grady Ward, 1.0:

79 Moby Thesaurus words for "commissary":
   PX, abundance, accumulation, amassment, backlog, budget,
   canned foods, canteen, caterer, chandler, collection, commissar,
   commissariat, commissionaire, commissioner, cornucopia, cumulation,
   dehydrated foods, delegate, donor, dump, emissary, envoy,
   food supply, fresh foods, frozen foods, furnisher, groceries,
   grocery, heap, herald, hoard, inventory, larder, legate, manciple,
   mass, material, materials, materiel, merchant, messenger, minister,
   munitions, patron, pile, plenitude, plenty, post exchange,
   provender, provider, provisioner, provisionment, provisions,
   purveyor, quartermaster, rations, repertoire, repertory, retailer,
   rick, secretary, stack, steward, stock, stock clerk,
   stock-in-trade, stockpile, store, storekeeper, stores, supplier,
   supplies, supply on hand, sutler, treasure, treasury, victualer,
   vivandier