If your mom orders you to clean your room, that's an order. If the king asks you to do it, that's an edict — an official order from some higher up.
Edict comes from the Latin editcum, meaning a "proclamation, or ordinance." Although it was originally used to describe a declaration or command from a king or other governing official, in more recent years it has come to be used almost sarcastically to describe any order. When your teacher says the report is due Monday morning, no exceptions, you know you'll be hitting the books this weekend — this is an edict you cannot ignore.