GNU Collaborative International Dictionary of English

Found one definition

1.       
   Fissile (?), a. [L. fissilis, fr. fissus, p. p. of findere to split. See Fissure.]
   1. Capable of being split, cleft, or divided in the direction of the grain, like wood, or along natural planes of cleavage, like crystals.
   
   [1913 Webster]
   
   This crystal is a pellucid, fissile stone. Sir I. Newton.
   
   [1913 Webster]
   
   
   2. Fissionable.
   
   [PJC]