[fis.sion] n [L fission-, fissio, fr. findere to split--more at bite] (ca. 1617) 1: a splitting or breaking up into parts
2: reproduction by spontaneous division of the body into two or more parts each of which grows into a complete organism
3: the splitting of an atomic nucleus resulting in the release of large amounts of energy -- fis.sion.al adj
[2]fission vi (1929): to undergo fission ~ vt: to cause to undergo fission