Fusion /(?)/

Fu·sion

Fusion

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

Phrases & Compounds
Watery fusion
the melting of certain crystals by heat in their own water of crystallization.