fiat
noun /ˈfiːæt/,  /ˈfiːət/
  /ˈfiːɑːt/
[countable, uncountable] (formal)- an official order given by somebody in authority synonym decree
- Prices have been fixed by government fiat.
 
Word Originlate Middle English: from Latin, ‘let it be done’, from fieri ‘be done or made’.