What does fratricide mean?
Fratricide denotes the act of killing one's own brother, and by extension a brother's or sibling's killing within a family. The word descends from Latin, combining 'frater' (brother) with '-cida' (killer), the same pattern that gives us patricide, matricide, and other compounds ending in '-cide'. Beyond its literal familial meaning, fratricide has a second established use in military terminology, where it names the accidental killing of friendly forces by their own side — what is popularly called 'friendly fire'. Culturally, the word carries heavy connotations of betrayal and tragedy: myths such as Romulus's slaying of Remus and countless literary works dramatise siblings turned against one another. Fratricide is a formal, somewhat grave term, encountered most often in history, law, literature, and defence writing rather than everyday conversation, yet it remains a powerful way to describe violence within families or among comrades.
nounThe act of killing one's own brother or sister; in military contexts, the accidental killing of friendly forces by their own side.
- The deliberate killing of one's own brother or sister.
- (Military) The unintended killing or wounding of friendly forces by one's own side, often called 'friendly fire'.
"The ancient myth of Romulus slaying Remus is often cited as the legendary fratricide that founded Rome."
"In Shakespeare's Hamlet, Claudius's murder of King Hamlet is fratricide as well as regicide."
"The investigation concluded that the soldier's death was a tragic case of fratricide caused by misdirected friendly fire."
Used when referring to multiple instances or events of fratricide.
"Several fratricides marked the succession struggles of the dynasty."
Rome's founding myth begins with an act of fratricide — Romulus killed his twin Remus in a quarrel over where the city walls should stand.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of fratricide
Fratricide derives from Latin, combining 'frater', meaning brother, with '-cida', meaning killer or slayer — the same Latinate pattern behind patricide, matricide, and tyrannicide. In classical Latin the term could also refer to the killing of a person in a brotherly relationship, such as between close friends or fellow citizens, reflecting Rome's horror at Cain-like violence within the civic family. The word passed into European legal and literary vocabulary, and English adopted it by at least the early modern period, later extending it to the modern military sense of friendly forces killed by their own side.
Related word forms
How fratricide is actually used
Fratricide carries strong connotations of betrayal and tragedy, and appears frequently in mythology, literature, and legal-historical writing. Its military sense — accidental deaths from friendly fire — is a formal term of art in defence contexts and differs sharply in intent from the familial sense.
Easily confused with fratricide
Sororicide is specifically the killing of one's sister, whereas fratricide is the killing of one's brother.
Patricide is the killing of one's father, while fratricide refers to killing one's brother.