Everyday is an adjective. In other words, it is used to add a characteristic to something. Generally, everyday is used to define something that you see every day. In other words, something typical, mundane, or common.
Every day, on the other hand is a phrase that means "each day" or "all days" depending on the context.
The pharse "HIC IACET ARTHURUS, REX QUONDAM REXQUE FUTURUS" from <u>"</u><u><em>The once and future king by T.H White" </em></u> <u>means: "Here lies Arthur, king once, king to be".</u>
It was a tomb inscription which promised that even Author was dead, he was going to return one day.
