The Collaborative International Dictionary of English v.0.48:

Apron \A"pron\ ([=a]"p[u^]rn or [=a]"pr[u^]n; 277), n. [OE.
   napron, OF. naperon, F. napperon, dim. of OF. nape, F. nappe,
   cloth, tablecloth, LL. napa, fr. L. mappa, napkin, table
   napkin. See Map.]
   1. An article of dress, of cloth, leather, or other stuff,
      worn on the fore part of the body, to keep the clothes
      clean, to defend them from injury, or as a covering. It is
      commonly tied at the waist by strings.
      [1913 Webster]

   2. Something which by its shape or use suggests an apron; as,
      (a) The fat skin covering the belly of a goose or duck.
          [Prov. Eng.] --Halliwell.
      (b) A piece of leather, or other material, to be spread
          before a person riding on an outside seat of a
          vehicle, to defend him from the rain, snow, or dust; a
          boot. "The weather being too hot for the apron."
          --Hughes.
      (c) (Gun.) A leaden plate that covers the vent of a
          cannon.
      (d) (Shipbuilding) A piece of carved timber, just above
          the foremost end of the keel. --Totten.
      (e) A platform, or flooring of plank, at the entrance of a
          dock, against which the dock gates are shut.
      (f) A flooring of plank before a dam to cause the water to
          make a gradual descent.
      (g) (Mech.) The piece that holds the cutting tool of a
          planer.
      (h) (Plumbing) A strip of lead which leads the drip of a
          wall into a gutter; a flashing.
      (i) (Zool.) The infolded abdomen of a crab.
          [1913 Webster]

WordNet (r) 3.0 (2006):

apron
    n 1: a garment of cloth or leather or plastic that is tied about
         the waist and worn to protect your clothing
    2: (golf) the part of the fairway leading onto the green
    3: the part of a modern theater stage between the curtain and
       the orchestra (i.e., in front of the curtain) [syn:
       proscenium, apron, forestage]
    4: a paved surface where aircraft stand while not being used

Moby Thesaurus II by Grady Ward, 1.0:

45 Moby Thesaurus words for "apron":
   L, R, acting area, airstrip, apron stage, backstage, band shell,
   bandstand, bib, board, bridge, clearway, coulisse, dock,
   dressing room, fairway, flies, flight deck, fly floor, fly gallery,
   forestage, greenroom, grid, gridiron, landing deck, landing strip,
   lightboard, orchestra, orchestra pit, performing area, pinafore,
   pit, proscenium, proscenium stage, runway, shell, smock, stage,
   stage left, stage right, strip, switchboard, the boards, tucker,
   wings



Easton's 1897 Bible Dictionary:

Apron
   found in the Authorized Version in Gen. 3:7, of the bands of
   fig-leaves made by our first parents. In Acts 19:12, it denotes
   the belt or half-girdle worn by artisans and servants round the
   waist for the purpose of preserving the clothing from injury. In
   marg. of Authorized Version, Ruth 3:15, correctly rendered
   instead of "vail." (R.V., "mantle.")