Source : Webster's Revised Unabridged Dictionary (1913)

Etching \Etch"ing\, n.
   1. The act, art, or practice of engraving by means of acid
      which eats away lines or surfaces left unprotected in
      metal, glass, or the like. See {Etch}, v. t.

   2. A design carried out by means of the above process; a
      pattern on metal, glass, etc., produced by etching.

   3. An impression on paper, parchment, or other material,
      taken in ink from an etched plate.

   {Etching figures} (Min.), markings produced on the face of a
      crystal by the action of an appropriate solvent. They have
      usually a definite form, and are important as revealing
      the molecular structure.

   {Etching needle}, a sharp-pointed steel instrument with which
      lines are drawn in the ground or varnish in etching.

   {Etching stitch} (Needlework), a stitch used outline
      embroidery.

Etch \Etch\, v. t. [imp. & p. p. {Etched}; p. pr. & vb. n.
   {Etching}.] [D. etsen, G. ["a]tzen to feed, corrode, etch.
   MHG. etzen, causative of ezzen to eat, G. essen ??. See
   {Eat}.]
   1. To produce, as figures or designs, on mental, glass, or
      the like, by means of lines or strokes eaten in or
      corroded by means of some strong acid.

   Note: The plate is first covered with varnish, or some other
         ground capable of resisting the acid, and this is then
         scored or scratched with a needle, or similar
         instrument, so as to form the drawing; the plate is
         then covered with acid, which corrodes the metal in the
         lines thus laid bare.

   2. To subject to etching; to draw upon and bite with acid, as
      a plate of metal.

            I was etching a plate at the beginning of 1875.
                                                  --Hamerton.

   3. To sketch; to delineate. [R.]

            There are many empty terms to be found in some
            learned writes, to which they had recourse to etch
            out their system.                     --Locke.

Source : WordNet®

etching
     n 1: an impression made from an etched plate
     2: an etched plate made with the use of acid
     3: making engraved or etched plates and printing designs from
        them [syn: {engraving}]