fiat

UK: /ˈfaɪət/

US: /ˈfiɑt, -æt; ˈfaɪət, -æt/

US: (fē′ät, -at; fī′ət, -at)

WordReference Random House Learner's Dictionary of American English © 2026

fi•at /ˈfiɑt, -æt; ˈfaɪət, -æt/   n. 

1. an authoritative decree;
   an official order:
   [countable] a royal fiat.
   [uncountable] to rule by fiat.

WordReference Random House Unabridged Dictionary of American English © 2026

fi•at  (fē′ät, -at; fī′ət, -at), n. 

1. an authoritative decree, sanction, or order:
   a royal fiat.
2. a formula containing the word fiat, by which a person in authority gives sanction.
3. an arbitrary decree or pronouncement, esp. by a person or group of persons having absolute authority to enforce it:
   The king ruled by fiat.

• Latin: let it be done, 3rd singular present subjunctive of fierī to become
• 1625–35

Collins Concise English Dictionary © HarperCollins Publishers::

fiat / ˈfaɪət -æt/ noun

1. official sanction; authoritative permission
2. an arbitrary order or decree

Etymology: 17th Century: from Latin, literally: let it be done, from fierī to become