Source : Webster's Revised Unabridged Dictionary (1913)

Calx \Calx\, n.; pl. E. {Calxes}, L. {Calces}. [L. Calx, calcis.
   limestone; cf. Gr. ? gravel. ?, ?, pebble, Skr. ? gravel, Ir.
   carraic rock Gael. carraig, W. careg, stone. Cf. {Chalk}.]
   1. (Chem.)
      (a) Quicklime. [Obs.]
      (b) The substance which remains when a metal or mineral
          has been subjected to calcination or combustion by
          heat, and which is, or may be, reduced to a fine
          powder.

   Note: Metallic calxes are now called oxides.

   2. Broken and refuse glass, returned to the post.

Source : WordNet®

calx
     n : a white crystalline oxide used in the production of calcium
         hydroxide [syn: {calcium oxide}, {quicklime}, {lime}, {calcined
         lime}, {fluxing lime}, {unslaked lime}, {burnt lime}]
     [also: {calces} (pl)]