A more thorough explanation:

Definition: Fratricide refers to the act of killing one's own brother or sister. It can also refer to a person who has committed such an act. The term "sororicide" is used specifically for the killing of one's sister.

Example: Cain's killing of his brother Abel in the Bible is an example of fratricide. Another example is the story of Romulus and Remus in Roman mythology, where Romulus kills his twin brother Remus in a dispute over the founding of Rome.

These examples illustrate how fratricide involves the killing of a sibling, which is considered a grave and heinous act in most cultures and societies.