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

But this focus on reforming the judiciary, combined with the politics of the period, meant that comparatively little attention was paid to the other two branches of government—and, in particular, to the slide toward rule by presidential fiat. —Gregg Nunziata, The Atlantic, 27 Apr. 2026

To my mind, going from one fiat to the other doesn't make sense — the true dollar diversifier is gold. —Michael Considine, CNBC, 23 Apr. 2026

Biden continued Covid-era moratoriums on evictions despite a Supreme Court ruling that found such fiat unconstitutional. —Letters To The Editor, Hartford Courant, 2 Apr. 2026

But is finishing by fiat actually finishing for real? —Joshua Rothman, New Yorker, 20 Mar. 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