Source : Webster's Revised Unabridged Dictionary (1913)

Pier \Pier\, n. [OE. pere, OF. piere a stone, F. pierre, fr. L.
   petra, Gr. ?. Cf. {Petrify}.]
   1. (Arch.)
      (a) Any detached mass of masonry, whether insulated or
          supporting one side of an arch or lintel, as of a
          bridge; the piece of wall between two openings.
      (b) Any additional or auxiliary mass of masonry used to
          stiffen a wall. See {Buttress}.

   2. A projecting wharf or landing place.

   {Abutment pier}, the pier of a bridge next the shore; a pier
      which by its strength and stability resists the thrust of
      an arch.

   {Pier glass}, a mirror, of high and narrow shape, to be put
      up between windows.

   {Pier table}, a table made to stand between windows.

Source : WordNet®

pier
     n 1: a platform built out from the shore into the water and
          supported by piles; provides access to ships and boats
          [syn: {wharf}, {wharfage}, {dock}]
     2: (architecture) a vertical supporting structure (as a portion
        of wall between two doors or windows)
     3: a support for two adjacent bridge spans