Source : Webster's Revised Unabridged Dictionary (1913)

Water glass \Wa"ter glass`\ (Chem.)
   See {Soluble glass}, under {Glass}.

Water glass \Water glass\
   1. A clepsydra.

   2. An instrument consisting of an open box or tube with a
      glass bottom, used for examining objects in the water, as
      upon the sea bottom in shallow places.

   3. A water gauge for a steam boiler.

Glass \Glass\, n. [OE. glas, gles, AS. gl[ae]s; akin to D., G.,
   Dan., & Sw. glas, Icel. glas, gler, Dan. glar; cf. AS.
   gl[ae]r amber, L. glaesum. Cf. {Glare}, n., {Glaze}, v. t.]
   1. A hard, brittle, translucent, and commonly transparent
      substance, white or colored, having a conchoidal fracture,
      and made by fusing together sand or silica with lime,
      potash, soda, or lead oxide. It is used for window panes
      and mirrors, for articles of table and culinary use, for
      lenses, and various articles of ornament.

   Note: Glass is variously colored by the metallic oxides;
         thus, manganese colors it violet; copper (cuprous),
         red, or (cupric) green; cobalt, blue; uranium,
         yellowish green or canary yellow; iron, green or brown;
         gold, purple or red; tin, opaque white; chromium,
         emerald green; antimony, yellow.

   2. (Chem.) Any substance having a peculiar glassy appearance,
      and a conchoidal fracture, and usually produced by fusion.

   3. Anything made of glass. Especially:
      (a) A looking-glass; a mirror.
      (b) A vessel filled with running sand for measuring time;
          an hourglass; and hence, the time in which such a
          vessel is exhausted of its sand.

                She would not live The running of one glass.
                                                  --Shak.
      (c) A drinking vessel; a tumbler; a goblet; hence, the
          contents of such a vessel; especially; spirituous
          liquors; as, he took a glass at dinner.
      (d) An optical glass; a lens; a spyglass; -- in the
          plural, spectacles; as, a pair of glasses; he wears
          glasses.
      (e) A weatherglass; a barometer.

   Note: Glass is much used adjectively or in combination; as,
         glass maker, or glassmaker; glass making or
         glassmaking; glass blower or glassblower, etc.

   {Bohemian glass}, {Cut glass}, etc. See under {Bohemian},
      {Cut}, etc.

   {Crown glass}, a variety of glass, used for making the finest
      plate or window glass, and consisting essentially of
      silicate of soda or potash and lime, with no admixture of
      lead; the convex half of an achromatic lens is composed of
      crown glass; -- so called from a crownlike shape given it
      in the process of blowing.

   {Crystal glass}, or {Flint glass}. See {Flint glass}, in the
      Vocabulary.

   {Cylinder glass}, sheet glass made by blowing the glass in
      the form of a cylinder which is then split longitudinally,
      opened out, and flattened.

   {Glass of antimony}, a vitreous oxide of antimony mixed with
      sulphide.

   {Glass blower}, one whose occupation is to blow and fashion
      glass.

   {Glass blowing}, the art of shaping glass, when reduced by
      heat to a viscid state, by inflating it through a tube.

   {Glass cloth}, a woven fabric formed of glass fibers.

   {Glass coach}, a coach superior to a hackney-coach, hired for
      the day, or any short period, as a private carriage; -- so
      called because originally private carriages alone had
      glass windows. [Eng.] --Smart.

            Glass coaches are [allowed in English parks from
            which ordinary hacks are excluded], meaning by this
            term, which is never used in America, hired
            carriages that do not go on stands.   --J. F.
                                                  Cooper.

   {Glass cutter}.
      (a) One who cuts sheets of glass into sizes for window
          panes, ets.
      (b) One who shapes the surface of glass by grinding and
          polishing.
      (c) A tool, usually with a diamond at the point, for
          cutting glass.

   {Glass cutting}.
      (a) The act or process of dividing glass, as sheets of
          glass into panes with a diamond.
      (b) The act or process of shaping the surface of glass by
          appylying it to revolving wheels, upon which sand,
          emery, and, afterwards, polishing powder, are applied;
          especially of glass which is shaped into facets, tooth
          ornaments, and the like. Glass having ornamental
          scrolls, etc., cut upon it, is said to be engraved.

   {Glass metal}, the fused material for making glass.

   {Glass painting}, the art or process of producing decorative
      effects in glass by painting it with enamel colors and
      combining the pieces together with slender sash bars of
      lead or other metal. In common parlance, glass painting
      and glass staining (see {Glass staining}, below) are used
      indifferently for all colored decorative work in windows,
      and the like.

   {Glass paper}, paper faced with pulvirezed glass, and used
      for abrasive purposes.

   {Glass silk}, fine threads of glass, wound, when in fusion,
      on rapidly rotating heated cylinders.

   {Glass silvering}, the process of transforming plate glass
      into mirrors by coating it with a reflecting surface, a
      deposit of silver, or a mercury amalgam.

   {Glass soap}, or {Glassmaker's soap}, the black oxide of
      manganese or other substances used by glass makers to take
      away color from the materials for glass.

   {Glass staining}, the art or practice of coloring glass in
      its whole substance, or, in the case of certain colors, in
      a superficial film only; also, decorative work in glass.
      Cf. Glass painting.

   {Glass tears}. See {Rupert's drop}.

   {Glass works}, an establishment where glass is made.

   {Heavy glass}, a heavy optical glass, consisting essentially
      of a borosilicate of potash.

   {Millefiore glass}. See {Millefiore}.

   {Plate glass}, a fine kind of glass, cast in thick plates,
      and flattened by heavy rollers, -- used for mirrors and
      the best windows.

   {Pressed glass}, glass articles formed in molds by pressure
      when hot.

   {Soluble glass} (Chem.), a silicate of sodium or potassium,
      found in commerce as a white, glassy mass, a stony powder,
      or dissolved as a viscous, sirupy liquid; -- used for
      rendering fabrics incombustible, for hardening artificial
      stone, etc.; -- called also {water glass}.

   {Spun glass}, glass drawn into a thread while liquid.

   {Toughened glass}, {Tempered glass}, glass finely tempered or
      annealed, by a peculiar method of sudden cooling by
      plunging while hot into oil, melted wax, or paraffine,
      etc.; -- called also, from the name of the inventor of the
      process, {Bastie glass}.

   {Water glass}. (Chem.) See {Soluble glass}, above.

   {Window glass}, glass in panes suitable for windows.

Source : WordNet®

water glass
     n 1: a viscous glass consisting of sodium silicate in solution;
          used as a cement or as a protective coating and to
          preserve eggs [syn: {soluble glass}, {sodium silicate}]
     2: a glass for drinking water
     3: gauge for indicating the level of water in e.g. a tank or
        boiler or reservoir [syn: {water gauge}, {water gage}]
     4: clock that measures time by the escape of water [syn: {water
        clock}, {clepsydra}]