Other forms: fiats
You might think a fiat is just an Italian car, but it actually means a legal, authoritative decision that has absolute sanction.
From the Latin for "let it be done," the word fiat is a binding edict issued by a person in command. It can gain an almost Biblical aura of authority, like a movie Pharaoh saying, "So let it be written, so let it be done." So let it be a fiat.