ax·​i·​om ˈak-sē-əm How to pronounce axiom (audio)
: a statement accepted as true as the basis for argument or inference : postulate sense 1
one of the axioms of the theory of evolution
: an established rule or principle or a self-evident truth
cites the axiom "no one gives what he does not have"
: a maxim widely accepted on its intrinsic merit
the axioms of wisdom

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In mathematics or logic, an axiom is an unprovable rule or first principle accepted as true because it is self-evident or particularly useful. “Nothing can both be and not be at the same time and in the same respect” is an example of an axiom. The term is often used interchangeably with postulate, though the latter term is sometimes reserved for mathematical applications (such as the postulates of Euclidean geometry). It should be contrasted with a theorem, which requires a rigorous proof.

Examples of axiom in a Sentence

one of the key axioms of the theory of evolution
Recent Examples on the Web Indeed, the whole affair may prove one of the most shopworn axioms of political reporting—that the coverup is worse than the crime. Jane Mayer, The New Yorker, 29 Feb. 2024 As Becky Wins And Stratton Shines For those who don’t know, first principles are an Aristotelian concept of finding axioms or ideas that don’t follow from any other proposition, theory or assumption. John Werner, Forbes, 24 Feb. 2024 See all Example Sentences for axiom 

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'axiom.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


borrowed from Middle French & Latin; Middle French axiome, borrowed from Latin axiōma "fundamental proposition," borrowed from Greek axíōma "honor, honored status, prestige, that which is reasonable (though not demonstrated to be true), self-evident principle," from axiō-, variant stem of axióō, axioûn "to consider worthy, value, consider appropriate, claim, think" (verbal derivative of áxios "valued [at a sum of money], worth, equal, of an equivalent status, worthy, suitable," of uncertain origin) + -ma, resultative noun suffix

Note: The Greek adjective áxios has conventionally been taken as originally meaning "of equal weight, counterbalancing"—hence it is seen as a derivative of an unattested noun *axis "weight" (< *ag-ti-), a derivative of ágein "to lead, carry off," also, among many other senses, "to weigh (a certain amount)," though the latter meaning is no earlier than fifth-century Attic.

First Known Use

15th century, in the meaning defined at sense 3

Time Traveler
The first known use of axiom was in the 15th century

Dictionary Entries Near axiom

Cite this Entry

“Axiom.” Dictionary, Merriam-Webster, Accessed 22 Apr. 2024.

Kids Definition


ax·​i·​om ˈak-sē-əm How to pronounce axiom (audio)
: a rule or principle widely accepted as obviously true and not needing to be proved
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