The Collaborative International Dictionary of English v.0.48:

Pile \Pile\, n. [F. pile, L. pila a pillar, a pier or mole of
   stone. Cf. Pillar.]
   1. A mass of things heaped together; a heap; as, a pile of
      stones; a pile of wood.
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   2. A mass formed in layers; as, a pile of shot.
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   3. A funeral pile; a pyre. --Dryden.
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   4. A large building, or mass of buildings.
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            The pile o'erlooked the town and drew the fight.
                                                  --Dryden.
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   5. (Iron Manuf.) Same as Fagot, n., 2.
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   6. (Elec.) A vertical series of alternate disks of two
      dissimilar metals, as copper and zinc, laid up with disks
      of cloth or paper moistened with acid water between them,
      for producing a current of electricity; -- commonly called
      Volta's pile, voltaic pile, or galvanic pile.
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   Note: The term is sometimes applied to other forms of
         apparatus designed to produce a current of electricity,
         or as synonymous with battery; as, for instance, to an
         apparatus for generating a current of electricity by
         the action of heat, usually called a thermopile.
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   7. [F. pile pile, an engraved die, L. pila a pillar.] The
      reverse of a coin. See Reverse.
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   Cross and pile. See under Cross.

   Dry pile. See under Dry.
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The Collaborative International Dictionary of English v.0.48:

Voltaic \Vol*ta"ic\, a. [Cf. F. volta["i]que, It. voltaico.]
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   1. Of or pertaining to Alessandro Volta, who first devised
      apparatus for developing electric currents by chemical
      action, and established this branch of electric science;
      discovered by Volta; as, voltaic electricity.
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   2. Of or pertaining to voltaism, or voltaic electricity; as,
      voltaic induction; the voltaic arc.
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   Note: See the Note under Galvanism.
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   Voltaic arc, a luminous arc, of intense brilliancy, formed
      between carbon points as electrodes by the passage of a
      powerful voltaic current.

   Voltaic battery, an apparatus variously constructed,
      consisting of a series of plates or pieces of dissimilar
      metals, as copper and zinc, arranged in pairs, and
      subjected to the action of a saline or acid solution, by
      which a current of electricity is generated whenever the
      two poles, or ends of the series, are connected by a
      conductor; a galvanic battery. See Battery, 4.
      (b), and Note.

   Voltaic circuit. See under Circuit.

   Voltaic couple or Voltaic element, a single pair of the
      connected plates of a battery.

   Voltaic electricity. See the Note under Electricity.

   Voltaic pile, a kind of voltaic battery consisting of
      alternate disks of dissimilar metals, separated by
      moistened cloth or paper. See 5th Pile.

   Voltaic protection of metals, the protection of a metal
      exposed to the corrosive action of sea water, saline or
      acid liquids, or the like, by associating it with a metal
      which is positive to it, as when iron is galvanized, or
      coated with zinc.
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WordNet (r) 3.0 (2006):

voltaic pile
    n 1: battery consisting of voltaic cells arranged in series; the
         earliest electric battery devised by Volta [syn: voltaic
         pile, pile, galvanic pile]