Source : Webster's Revised Unabridged Dictionary (1913)

Sandstone \Sand"stone`\, n.
   A rock made of sand more or less firmly united. Common or
   siliceous sandstone consists mainly of quartz sand.

   Note: Different names are applied to the various kinds of
         sandstone according to their composition; as, granitic,
         argillaceous, micaceous, etc.

   {Flexible sandstone} (Min.), the finer-grained variety of
      itacolumite, which on account of the scales of mica in the
      lamination is quite flexible.

   {Red sandstone}, a name given to two extensive series of
      British rocks in which red sandstones predominate, one
      below, and the other above, the coal measures. These were
      formerly known as the Old and the New Red Sandstone
      respectively, and the former name is still retained for
      the group preceding the Coal and referred to the Devonian
      age, but the term New Red Sandstone is now little used,
      some of the strata being regarded as Permian and the
      remained as Triassic. See the Chart of {Geology}.

Source : WordNet®

sandstone
     n : a sedimentary rock consisting of sand consolidated with some
         cement (clay or quartz etc.)