vt the union, or binding together, of adjacent parts or tissues.
2. fusion ·vt the union or blending together of things, as, melted together.
3. fusion ·vt the act or operation of melting or rendering fluid by heat; the act of melting together; as, the fusion of metals.
4. fusion ·vt the state of being melted or dissolved by heat; a state of fluidity or flowing in consequence of heat; as, metals in fusion.