Tyrion Lannister: What's the punishment for regicide? Drawing and quartering? Hanging? Breaking at the wheel?
Jaime Lannister: Beheading.
Tyrion Lannister: Seems rather ordinary. And he was my nephew as well, so what is that? Fratricide is brothers. Filicide is sons. Nepoticide. That's the one. Matricide, patricide, infanticide, suicide. There's no kind of killing that doesn't have its own word.
Jaime Lannister: Cousins.
Tyrion Lannister: Cousins, you're right. There is no word for cousin killing.