Source : Webster's Revised Unabridged Dictionary (1913)

Topaz \To"paz\, n. [OE. topas, F. topaze, L. topazos, or
   topazion, a kind of precious stone, Gr. to`pazos, topa`zion;
   possibly akin to Skr. tap to glow (cf. {Tepid}). According to
   some, the name is from Topazos, a small island in the Red
   Sea, where the Romans obtained a stone which they called by
   this name, but which is the chrysolite of the moderns.]
   1. (Min.) A mineral occurring in rhombic prisms, generally
      yellowish and pellucid, also colorless, and of greenesh,
      bluish, or brownish shades. It sometimes occurs massive
      and opaque. It is a fluosilicate of alumina, and is used
      as a gem.

   2. (Zo["o]l.)Either one of two species of large, brilliantly
      colored humming birds of the {Topaza}, of South America
      and the West Indies.

   Note: The two tail feathers next to the central ones are much
         longer that the rest, curved, and crossed. The Throat
         is metallic yellowish-green, with a tint like topaz in
         the center, the belly is bright crimson, the back
         bright red. Called also {topaz hummer}.

   {False topaz}. (Min.) See the Note under {Quartz}.

Source : WordNet®

false topaz
     n : a yellow quartz [syn: {topaz}, {common topaz}]