fiat

noun

fi·​at ˈfē-ət 

-ˌat, 

-ˌät;

ˈfī-ət, 

-ˌat 

1

: an authoritative or arbitrary order : decree

government by fiat

2

: an authoritative determination : dictate

a fiat of conscience

3

: a command or act of will that creates something without or as if without further effort

According to the Bible, the world was created by fiat.

Synonyms of fiat

• decree
• edict
• ruling
• directive

Examples of fiat in a Sentence

He runs the company by fiat.

the school principal issued a fiat that caps were not to be worn inside the school, and that was that

Recent Examples on the Web

Perhaps the most important impact of having term limits banned by judicial fiat has been that on national spending. —Boston Herald Editorial Staff, Boston Herald, 27 Feb. 2026

Trump loves tariffs, which are nothing more than massive tax increases imposed by fiat on America’s consumers. —Steven Greenhut, Oc Register, 27 Feb. 2026

And perhaps most important, by empowering Congress, not the president, to remedy deficient state electoral schemes, the Constitution prevents presidents from rewriting the election code by executive fiat and thus provides an additional safeguard against military dictatorship. —Jeffrey Rosen, The Atlantic, 16 Feb. 2026

Users can manage funds in a mix of fiat and cryptocurrency — including holdings like Bitcoin and Ethereum — and transact globally with a single card or digital wallet. —Nia Bowers, USA Today, 1 Feb. 2026

Word History

Etymology

Latin, let it be done, 3rd singular present subjunctive of fieri to become, be done — more at be

First Known Use

circa 1631, in the meaning defined at sense 3

Phrases Containing fiat

• fiat money

Kids Definition

fiat

noun

fi·​at ˈfē-ət  -at 

-ät;

ˈfī-ət, 

-at

: an order from someone in charge

Legal Definition

fiat

noun

fi·​at ˈfē-ˌät, -ˌat, -ət; ˈfī-ˌat 

1

: decree

2

: an authoritative but arbitrary order

a brazen act of judicial fiat

—L. H. Tribe