The Collaborative International Dictionary of English v.0.48:

Fissiparous \Fis*sip"a*rous\, a. [L. fissus (p. p. of findere to
   split) + parere to bring forth: cf. F. fissipare.] (Biol.)
   Reproducing by spontaneous fission. See Fission. --
   Fis*sip"a*rous*ly, adv.
   [1913 Webster]

WordNet (r) 3.0 (2006):

fissiparous
    adj 1: reproducing by fission
    2: having separated or advocating separation from another entity
       or policy or attitude; "a breakaway faction" [syn:
       breakaway, fissiparous, separatist]