Source : Webster's Revised Unabridged Dictionary (1913)

Mason \Ma"son\, n. [F. ma?on, LL. macio, machio, mattio, mactio,
   marcio, macerio; of uncertain origin.]
   1. One whose occupation is to build with stone or brick;
      also, one who prepares stone for building purposes.

   2. A member of the fraternity of Freemasons. See {Freemason}.

   {Mason bee} (Zo["o]l.), any one of numerous species of
      solitary bees of the genus {Osmia}. They construct curious
      nests of hardened mud and sand.

   {Mason moth} (Zo["o]l.), any moth whose larva constructs an
      earthen cocoon under the soil.

   {Mason shell} (Zo["o]l.), a marine univalve shell of the
      genus {Phorus}; -- so called because it cements other
      shells and pebbles upon its own shell; a carrier shell.

   {Mason wasp} (Zo["o]l.), any wasp that constructs its nest,
      or brood cells, of hardened mud. The female fills the
      cells with insects or spiders, paralyzed by a sting, and
      thus provides food for its larv[ae]

Source : WordNet®

mason bee
     n : any of numerous solitary bees that build nests of hardened
         mud and sand