[frat.ri.cide] n [in sense 1, fr. ME, fr. MF or L; MF, fr. L fratricida, fr. fratr-, frater brother + -cida -cide; in sense 2, fr. MF or L; MF, fr. L fratricidium, fr. fratr-, frater + -cidium -cide] (15c) 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 -- frat.ri.cid.al adj