the act or process of fusing
the union of light atomic nuclei to form heavier nuclei, resulting in the release of enormous quantities of energy
a union formed when two things fuse; a merging
a blend of two or more styles, e.g. in music, cookery, or design
When jazz musicians began applying rock rhythms to their work, around 1970, the hybrid term jazz-rock was used to describe the results, but this subsequently gave way to the more all-embracing term ‘fusion’. Besides this generic application, it has grown into a widely used epithet for virtually any amalgamation, induced or otherwise, of popular instrumental forms — Richard Cook
[Latin fusion-, fusio, from fundere to pour, melt]