A reaction in which two or more atomic nuclei come close enough to form one or more different atomic nuclei and subatomic particles (neutrons and/or protons). The difference in mass between the products and reactants is manifested as the release of large amounts of energy.
Nuclear reaction which happens when Kim Kardashian farts. It is caused by extreme pressure between the cheeks of her butt, which forces hydrogenatoms to fuse with one another, creating a chain reaction which annihilates all forms of life from the surface of Earth, except her followers.