a priori

adjective

a pri·​o·​ri ˌä-prē-ˈȯr-ē 

ˌa-;

ˌā-(ˌ)prī-ˈȯr-ˌī 

-ˌprē-ˈȯr-ē

1

a

: being without examination or analysis : presumptive

In defense of this proposition and in his appeal to skeptics, [author Garland] Grimes relies upon the evidence of history rather than an a priori acceptance of the Bible.

—PR Newswire

b

: formed or conceived beforehand

A priori predictions of the consequences of nuclear war will always be subject to uncertainties …

—John Walsh

2

a

: of, relating to, or provable by deduction : deductive

a priori reasoning

an a priori argument

b

: relating to or derived by reasoning from self-evident propositions compare a posteriori

c

: presupposed by experience

a priori adverb

apriority

ˌä-prē-ˈȯr-ə-tē, 

ˌa-;

  ˌā-(ˌ)prī-ˈȯr- 

-ˌprē-ˈȯr

noun

Did you know?

A priori and a posteriori are terms that are used especially in logic and philosophy. A priori is from Latin ā priōrī, which means literally, "from what is earlier." A priori knowledge is knowledge that comes from the power of reasoning based on self-evident truths; a priori usually describes lines of reasoning or arguments that proceed from the general to the particular, or from causes to effects. A posteriori is from Latin ā posteriōrī, which means literally, "from what is later." It describes knowledge based solely on experience or personal observation. So, for example, "Every apple is a fruit" is an a priori statement, since it shows simple logical reasoning and isn't a statement of fact about a specific case; "apples are sweet" is a posteriori, as it expresses something the speaker knows from experience.

Synonyms of a priori

• inferable
• derivable
• reasoned

Examples of a priori in a Sentence

There's no a priori reason to think your expenses will remain the same in a new city.

an a priori argument for the defendant's innocence

Recent Examples on the Web

But its deterioration is a profound a priori, one that can only be partially forestalled. — Jeffrey Weiss, Artforum, 1 Oct. 2026

Its students arrive morally outraged, a priori puritans, while its professors are enervated and dissatisfied. — Zain Khalid, Vulture, 1 Oct. 2026

Research into sparse, a priori network topologies, architectures like NeuroFab, start sparse rather than pruning dense networks after training. — Amir Husain, Forbes.com, 13 Mar. 2026

This sort of a priori justification for ESAs explains a few things. — Chandler Fritz, Harpers Magazine, 20 Aug. 2025

Word History

Etymology

borrowed from Medieval Latin ā priōrī literally, "from what is earlier"

First Known Use

1570, in the meaning defined at sense 2a

Rhymes for a priori

• aurore
• forbore
• outlawry
• pylori
• savoury
• signori
• signory
• vainglory
• accusatory
• admonitory
• ambulatory
• amendatory