The Collaborative International Dictionary of English v.0.48:

Vat \Vat\ (v[a^]t), n. [A dialectic form for fat, OE. fat, AS.
   f[ae]t; akin to D. vat, OS. fat, G. fass, OHG. faz, Icel. &
   Sw. fat, Dan. fad, Lith. p[*u]das a pot, and probably to G.
   fassen to seize, to contain, OHG. fazz[=o]n, D. vatten. Cf.
   Fat a vat.]
   [1913 Webster]
   [1913 Webster]
   1. A large vessel, cistern, or tub, especially one used for
      holding liquors in an immature state, chemical
      preparations for dyeing, or for tanning, or for tanning
      leather, or the like.
      [1913 Webster]

            Let him produce his vats and tubs, in opposition to
            heaps of arms and standards.          --Addison.
      [1913 Webster]

   2. A measure for liquids, and also a dry measure; especially,
      a liquid measure in Belgium and Holland, corresponding to
      the hectoliter of the metric system, which contains 22.01
      imperial gallons, or 26.4 standard gallons in the United
      States.
      [1913 Webster]

   Note: The old Dutch grain vat averaged 0.762 Winchester
         bushel. The old London coal vat contained 9 bushels.
         The solid-measurement vat of Amsterdam contains 40
         cubic feet; the wine vat, 241.57 imperial gallons, and
         the vat for olive oil, 225.45 imperial gallons.
         [1913 Webster]

   3. (Metal.)
      (a) A wooden tub for washing ores and mineral substances
          in.
      (b) A square, hollow place on the back of a calcining
          furnace, where tin ore is laid to dry.
          [1913 Webster]

   4. (R. C. Ch.) A vessel for holding holy water.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Vat \Vat\, v. t. [imp. & p. p. Vatted; p. pr. & vb. n.
   Vatting.]
   To put or transfer into a vat.
   [1913 Webster]

WordNet (r) 3.0 (2006):

VAT
    n 1: a tax levied on the difference between a commodity's price
         before taxes and its cost of production [syn: VAT,
         value-added tax, ad valorem tax]
    2: a large open vessel for holding or storing liquids [syn:
       tub, vat]

Moby Thesaurus II by Grady Ward, 1.0:

59 Moby Thesaurus words for "vat":
   archives, armory, arsenal, attic, bank, basement, bay, bin,
   bonded warehouse, bookcase, box, bunker, buttery, cargo dock,
   cellar, chest, closet, conservatory, crate, crib, cupboard,
   depository, depot, dock, drawer, dump, exchequer, glory hole,
   godown, hold, hutch, library, locker, lumber room, lumberyard,
   magasin, magazine, rack, repertory, repository, reservoir, rick,
   shelf, stack, stack room, stock room, storage, store, storehouse,
   storeroom, supply base, supply depot, tank, treasure house,
   treasure room, treasury, vault, warehouse, wine cellar



V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

VAT
       [UDF] Virtual Allocation Table (UDF, CD-R)