A cleaving, splitting, or breaking up into parts.
- The act or process of splitting into parts.
- A nuclear reaction in which an atomic nucleus, especially a heavy nucleus such as an isotope of uranium, splits into fragments, usually two fragments of comparable mass, releasing from 100 million to several hundred million electron volts of energy.
- Biology An asexual reproductive process in which a unicellular organism divides into two or more independently maturing daughter cells.
- To cause (an atom) to undergo fission.
- To undergo fission.