fis·sion (fishən, fizh-)
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 but unequal mass, and releases a few neutrons and about 100 million electron volts of energy. Nuclear fission may occur spontaneously or may be induced by the absorption of a neutron, which can initiate a nuclear chain reaction.
3. Biology An asexual reproductive process in which a unicellular organism divides into two or more independently maturing daughter cells.
v.fis·sioned, fis·sion·ing, fis·sions
To cause (an atom) to undergo fission.
To undergo fission.
[Latinfissiō, fissiōn-, a cleaving, fromfissus, split; see FISSI–.]
(click for a larger image)fission
fission of a uranium nucleus
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