(bokmål) fisjon betyr engelsk

fission [fissions]▼(process whereby one item splits to become two)
noun
[UK: ˈfɪʃ.n̩] [US: ˈfɪʃ.n̩]

nuclear fission▼(atom-splitting nuclear reaction)
noun
[UK: ˈnjuː.klɪə(r) ˈfɪʃ.n̩] [US: ˈnuː.kliər ˈfɪʃ.n̩]