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

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

These new loops manufacture demand, legitimacy, and cultural weight—not because of what the content says, but because of how it was engineered a priori. —Emil Steiner, Forbes.com, 14 Aug. 2025

One of his most significant contributions was introducing new mathematical tools to model and incorporate a priori data—which relies on deductive reasoning to make predictions—to address signal recovery challenges. —IEEE Spectrum, 3 Oct. 2024

Knowing a priori which stocks will outperform the market is also much more difficult than reviewing the trends that occurred in the past. —Wayne Winegarden, Forbes, 2 Oct. 2024

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

• allegory
• amatory
• auditory
• category
• clerestory
• crematory
• desultory
• dilatory
• dormitory
• excretory
• extempore
• feudatory