A person who is incredibly cocky and selfcentered. Thinks he is strong enough to take anyone. An Arxium is also someone who is hated by everyone. Arxium is also expected to be friendzoned by all the girls in his school. (Prefferably used on a guy).
"Man look at that Arxium. Whats his name again?"
"Hes Mathew Chan... He is totally a Arxium."