The Meaning of A Priori: What It Is and How To Use It

What does the phrase a priori mean, and how is it used in sentences? This article will teach you all about the meaning of a priori and how to use it.

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Do you know what the Latin phrase a priori means? This article shall teach you all about the term a priori and how to use it in deductive reasoning.

You may not realize it, but many words and phrases that we use in English are Latin phrases. For example, a priori is a phrase that the English language takes directly from Latin. In this article, you will not only learn what a priori means but also the meanings of several other Latin phrases.

What Does A Priori Mean?

According to Dictionary, a priori means valid independently of evidence, experience, or observation. This term is often applied to knowledge accepted as true without previous observation or experience. You might see the phrase a priori appear in deductive reasoning. The pronunciation of a priori is ˌeɪ praɪˈɔraɪ.

The term a priori can either be an adjective or an adverb. A priori is the opposite of a posteriori, another Latin phrase. Things that are true a posteriori are based on observation, experience, and data. 

Unlike a priori statements, which involve deductive reasoning, a posteriori statements involve inductive reasoning. You might see both a priori and a posteriori in philosophy and epistemology. 

What Is the Etymology of A Priori?

The term a priori entered the English language in the mid-1600s. It came directly from the Medieval Latin ā priōrī, which means “from the one before” or “from the previous.” A posteriori also comes directly from the Latin language and translates to “from the behind” or “from the latter.”

Immanuel Kant popularized both of these phrases in his book Critique of Pure Reason, a 1781 publication that studies the distinction between empirical knowledge and non-empirical knowledge. 

What Are Examples of A Priori?

A priori is a phrase that you might not hear very often. Study the below example sentences containing a priori to get a sense of how to use this Latin phrase in everyday life.  

Sometimes I use a priori knowledge to make decisions, but other times I make them based on evidence.

All of the evidence went against the a priori argument, but the jury still had trouble deciding the result of the case.

I was frustrated that my partner had formed an a priori judgment rather than one based on observed facts.

The man decided to move to New York for an a priori reason.

What Are Synonyms of A Priori?

Power Thesaurus lists several words that people can use in place of a priori. If someone is not familiar with the Latin phrase a priori, you can replace it with one of the below. Knowing different ways to say certain words and phrases is always useful.

  • analytical
  • apparent
  • assertive
  • attributable
  • authoritarian
  • authoritative
  • axiomatic
  • be inferred
  • by fiat
  • by natural law
  • canonical
  • categorical
  • clear
  • cogent
  • consequent
  • consequential
  • consistent
  • deducible
  • deductive
  • deductively
  • derivable
  • dogmatic
  • evident
  • extractable
  • following
  • from the earlier
  • from theory
  • illative
  • inducible
  • inferable
  • inferential
  • inferred
  • intuitively obvious
  • logical
  • manifest
  • obtainable
  • obvious
  • on faith
  • patent
  • plain
  • prima facie
  • priori
  • provable
  • rational
  • reasoned
  • relevant
  • scientifically
  • self-evident
  • sound
  • theoretically
  • traceable
  • valid
  • well reasoned
  • well thought out

What Are Antonyms of A Priori?

Power Thesaurus also lists words that mean the opposite of a priori.

  • a posteriori
  • appeared
  • appearing
  • at the first blush
  • authentic
  • conclusive
  • concrete
  • connotative
  • corporeal
  • counter-evidential
  • decisive
  • demonstrated
  • demonstrative
  • diagnostic
  • discernible
  • displayed
  • documented
  • emblematic
  • embodied
  • evidence
  • evidence-based
  • evidential
  • evidentiary
  • evincive
  • exemplified
  • exhibited
  • expressive
  • factual
  • incarnate
  • indicative
  • indicatory
  • informational
  • knowable
  • manifested
  • materialized
  • meaningful
  • observable
  • ominous
  • palpable
  • perceivable
  • pointing to
  • present
  • presumptive
  • prima facie
  • probative
  • probatory
  • proved
  • proven
  • revealed
  • shown
  • significant
  • significatory
  • suggestive
  • symbolic
  • symptomatic
  • tangible
  • testatory
  • testified
  • viewable
  • visible

What Are Other Latin Phrases?

You may not realize it, but people use several Latin phrases in English! Take a look at these common Latin phrases. While other words might originate from the Latin language, all of the below are phrases that we still use in the original Latin. 

How many of these Latin terms have you used before?

  • ad hoc: done or created for one particular purpose
  • in vitro: outside a living organism 
  • et cetera; etc.: and so on; and more
  • per annum; p.a.: for each year
  • post-mortem: an examination of a body after death; autopsy
  • in situ: in its original place
  • persona non grata: unacceptable or unwelcome person
  • ex gratia: from kindness or grace 
  • verbatim: in exactly the same words
  • status quo: existing state of affairs
  • de facto: in fact; in reality
  • in loco parentis: in place of a parent
  • sine qua non: essential condition; something that is necessary
  • vice versa: the other way round
  • coitus interruptus: literally interrupted congress; the ending of sexual intercourse before ejaculation
  • ergo: therefore
  • inter alia: among other things
  • ad nauseam: continuing or repeating to the point of boredom
  • per se: in itself/themselves; intrinsically
  • compos mentis: in control of the mind
  • terra firma: dry land
  • circa; c.: around; approximately
  • ex libris: from the library
  • habeas corpus: a court order which mandates that a person under arrest be brought before a judge
  • bona fide: genuine; real
  • pro rata: proportional; proportionally
  • versus; vs.; v.: against
  • quid pro quo: favor or advantage given or expected in return for something
  • per: for each
  • re: about; concerning; regarding
  • caveat emptor: let the buyer beware
  • erratum: error; mistake
  • per capita: for each person


Overall, the definition of a priori is deductible or discernible independent of observation or experience. This word of the day is a Latin phrase.


  1. A Priori synonyms – 28 Words and Phrases for A Priori | Power Thesaurus  
  2. 208 Words and Phrases for Evidential | Power Thesaurus 
  3. A priori Definition & Meaning |