Source : Webster's Revised Unabridged Dictionary (1913)

Fratricide \Frat"ri*cide\, n. [L. fratricidium a brother's
   murder, fr. fratricida a brother's murderer; frater, fratris,
   brother + caedere to kill: cf. F. fratricide.]
   1. The act of one who murders or kills his own brother.

   2. [L. fratricida: cf. F. fratricide.] One who murders or
      kills his own brother.

Source : WordNet®

fratricide
     n 1: a person who murders their brother or sister
     2: the act of murdering your own brother or sister
     3: fire that injures or kills an ally [syn: {friendly fire}]