Source : Webster's Revised Unabridged Dictionary (1913)

Fusion \Fu"sion\, n. [L. fusio, fr. fundere, fusum to pour,
   melt: cf. F. fusion. See {Fuse}, v. t., aud cf, {Foison}.]
   1. The act or operation of melting or rendering fluid by
      heat; the act of melting together; as, the fusion of
      metals.

   2. The state of being melted or dissolved by heat; a state of
      fluidity or flowing in consequence of heat; as, metals in
      fusion.

   3. The union or blending together of things, as, melted
      together.

            The universal fusion of races, languages, and
            customs . . . had produced a corresponding fusion of
            creeds.                               --C. Kingsley.

   {Watery fusion} (Chem.) the melting of certain crystals by
      heat in their own water of crystallization.

   4. (Biol.) The union, or binding together, of adjacent parts
      or tissues.