fission

(fĭshˈən)

1. The act or process of splitting into parts.
2. 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.
3. Biology An asexual reproductive process in which a unicellular organism divides into two or more independently maturing daughter cells.

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fission

fission of a uranium nucleus