1. the killing of one's brother or sister: "Cain justifies his fratricide with lethal logic"
▪ a person who kills their brother or sister.
▪ the accidental killing of one's own forces in war:"the Vietnam War saw fratricide increase because of the close-in jungle fighting"
Word Originlate 15th century (denoting a person who kills their brother or sister, derived from Latin fratricida): the primary current sense comes via French from late Latin fratricidium, from frater ‘brother’ + -cidium (see -cide).