nuclear fusionnuclear fusion
Nuclear fusion is when two or more lightweight atoms join together to form one heavier nucleus, with any energy released due to the conversion being converted into nuclear energy.
An example of nuclear fusion is the process of four hydrogens coming together to form helium.
the fusion of lightweight atomic nuclei, as of tritium or deuterium, into a nucleus of heavier mass, as of helium: the resultant loss in combined mass is converted into energy
(usually uncountable, plural nuclear fusions)