The definition of permanent.
Per·ma·nent ˈpərmənənt/Submit adjective 1. lasting or intended to last or remain unchanged indefinitely.
In·def·i·nite ˌinˈdef(ə)nət/Submit adjective lasting for an unknown or unstated length of time.
Weird. I was 100% certain that permanent meant forever.
Oh well, the more you know, right?
Edit: I don't really care about getting downvoted, but I should probably clarify that this post is not intended in any way, shape or form to be a case for permanently banned accounts to be lifted. I believe in Riot's judgement.