fission          
noun [ U ] uk/ˈfɪʃ.ən/ us/ˈfɪʃ.ən/
 physics specialized(核)裂变,分裂 
the process of dividing the nucleus of an atom, resulting in the release of a large amount of energy 
  nuclear fission 核裂变 
  biology specialized细胞分裂;裂殖 
the division of a living cell as part of reproduction
  The fission of the cell could be inhibited with certain chemicals. 细胞裂殖可以靠某些化学制品加以抑制。