Learner's definition of FUSION
1 : a combination or mixture of things
a fusion of different methods
a fusion of musical styles
The show is a fusion of news and entertainment.
2 [noncount], physics : a process in which the nuclei of atoms are joined
◊ A large amount of energy is released when fusion occurs.
— called also nuclear fusion
3 [noncount] : a type of popular music that combines different styles (such as jazz and rock) 4 [noncount] : food prepared by combining methods and ingredients from different areas of the world
— called also fusion cuisine