fratricide n[Middle French, from Latin fratricida , from fratr - frater brother + -cida killing]
1 : one that murders or kills his or her own brother or sister or an individual (as a countryman) having a relationship like that of a brother or sister
2 : the act of a fratricide
Source: Merriam-Webster's Dictionary of Law ©1996. Merriam-Webster, Incorporated. Published under license with Merriam-Webster, Incorporated.