If Arthas "was a fratricide" then he would have been killed by a sibling.

Also a regicide!

Slowing down a bit: One can be a victim of fratricide, and one can go on a fratricidal rage, but "fratricide" is a noun, not a verb. You cannot "fratricide" anyone in the same way that you cannot "printer" anyone.

For what it's worth, "fratricide" is specifically if you kill your brother—it's from "frater" in Latin. If Arthas killed his sister he'd be a sororicide. (Think of the "fraternity" / "sorority" difference.)

...yes, I'm a Latin nerd. :)

@Samlowry

Fratricide is both an abstract noun (describing the act of killing one's brother - "He commited fratricide") or a concrete noun describing one who has killed his own brother ("He killed his brother, he is a fratricide"). If Arthas had been killed by his brother he would be a "victim of fratricide", not a fratricide himself.

Arthas was neither of these - he was a patricide and a regicide (although it's notable that sometimes "regicides" were called "patricides" even if they were not the children of the kind - this referred to the role of Kings as "fathers of the nation", and so any one of the King's subjects would be commiting patricide if they murdered him).

Thanks Kurash, I wondered if it was the same in English (I'm French - and a language nerd too :P).

Language nerds unite! :)