The Collaborative International Dictionary of English v.0.48:

Pile \Pile\, v. t. [imp. & p. p. Piled; p. pr. & vb. n.
   Piling.]
   1. To lay or throw into a pile or heap; to heap up; to
      collect into a mass; to accumulate; to amass; -- often
      with up; as, to pile up wood. "Hills piled on hills."
      --Dryden. "Life piled on life." --Tennyson.
      [1913 Webster]

            The labor of an age in piled stones.  --Milton.
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   2. To cover with heaps; or in great abundance; to fill or
      overfill; to load.
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   To pile arms To pile muskets (Mil.), to place three guns
      together so that they may stand upright, supporting each
      other; to stack arms.
      [1913 Webster] Pileate

The Collaborative International Dictionary of English v.0.48:

Piling \Pil"ing\, n. [See Pile a heap.]
   1. The act of heaping up.
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   2. (Iron Manuf.) The process of building up, heating, and
      working, fagots, or piles, to form bars, etc.
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The Collaborative International Dictionary of English v.0.48:

Piling \Pil"ing\, n. [See Pile a stake.]
   A series of piles; piles considered collectively; as, the
   piling of a bridge.
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   Pug piling, sheet piles connected together at the edges by
      dovetailed tongues and grooves.

   Sheet piling, a series of piles made of planks or half logs
      driven edge to edge, -- used to form the walls of
      cofferdams, etc.
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WordNet (r) 3.0 (2006):

piling
    n 1: a column of wood or steel or concrete that is driven into
         the ground to provide support for a structure [syn: pile,
         spile, piling, stilt]