The term "fusion" (from English fusion - merging, combination) has several meanings depending on the context. Fusion is when different cultures mix their best elements to create something new and interesting. In music, this can mean the merging of different musical styles, such as jazz and rock. Imagine a band where the saxophone plays alongside the electric guitar — it's no longer just jazz or rock, but something else, unique. A great example is the music of the band Red Hot Chili Peppers, who skillfully combine rock, funk, and hip-hop.
In cooking, fusion means mixing different cuisines. It's when a chef takes, say, a cooking technique from French cuisine, adds ingredients from Japanese, and creates something completely new. Maybe you've seen a roll in a sushi restaurant where instead of rice — there's a bread-like toast? That's culinary fusion.
This term is also used in science.
Nuclear fusion is the process of merging atomic nuclei, which occurs, for example, in the hearts of stars. Humanity is trying to replicate it to create clean energy (as an alternative to nuclear fission reactors).
By the way, it is correct to write "fusion," that is, with an apostrophe, and not with a soft sign - "fyužin".