Definition of: fusion

(fy′zhən) noun
1. The act of blending, or the state of being blended throughout.
2. The act of coalescing of two political parties, or the state of coalescence: also used attributively: a fusion ticket.
3. The act or process of changing, or the state of being in the course of change, from a solid into a liquid by the agency of heat; melting.
4. A state of fluidity due to the action of heat.
5. Physics A thermonuclear reaction in which the nuclei of a light element undergo transformation into those of a heavier element, with the release of great energy: the reverse of fission.
6. Ling. A coalescing of two originally distinct words because of a similarity in form and meaning, as in the development of the verb bid from the Old English verbs biddan “ask” and bēodan “command.” See synonyms under ALLIANCE. [<L fusio, -onis <fundere pour]