assertion

From Middle English assercioun, from Latin assertiō.^[1] By surface analysis, assert +‎ -ion.

• (Received Pronunciation) IPA^(key): /əˈsɜːʃən/
• (General American) IPA^(key): /əˈsɜɹʃən/, [əˈsɝʃn̩]

• Audio (US):

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• Audio (UK):

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  Rhymes: -ɜː(ɹ)ʃən

assertion (countable and uncountable, plural assertions)

1. The act of asserting; positive declaration or averment.
2. Something which is asserted; a declaration; a statement asserted.

   Synonym: contention

   You're a man of strong assertions!

   • 2007 January 26, Ruth M. J. Byrne, The Rational Imagination: How People Create Alternatives to Reality‎^[1], MIT Press, →ISBN, page 140:

     Suppose you are given the semifactual assertion, "even if Nora had liked mathematics then she would have became^[sic] a scientist" and then you find out that Nora did in fact become a scientist.

3. A statement or declaration which lacks support or evidence.

   That's just a bare assertion.

   • 2022 August 24, Philip Haigh, “Network News: Union slams Avanti West Coast: 'lie' as services slashed”, in RAIL, number 964, page 6:

     Drivers' union ASLEF bluntly rebuffed the claim of unofficial action, calling it a lie. And Avanti West Coast was unable to provide any proof for its assertion, when questioned by RAIL.

   • 2026 February 27, Jennifer Hansler, Natasha Bertrand, Kylie Atwood, Zachary Cohen, “Trump has claimed Iran is building missiles that could soon hit the US. Sources say that’s not backed up by US intelligence.”, in CNN‎^[2], archived from the original on 3 March 2026:

     However, that assertion is not backed up by US intelligence, sources told CNN. […] That claim came despite the Trump administration’s repeated assertions that the US had “obliterated” Iran’s nuclear program in military strikes last year.

4. Maintenance; vindication.

   the assertion of one's rights or prerogatives

5. (programming) A statement in a program asserting a condition expected to be true at a particular point, used in debugging.
   • 2006, Srikanth Vijayaraghavan, Meyyappan Ramanathan, A Practical Guide for SystemVerilog Assertions, page 284:

     The user should be absolutely confident that the error issued is a real design error. In other words, a user should be confident that his assertion code is correct and that the assertion failure is not a false condition.

6. (finance) The set of information that the statement preparer is providing in a financial statement audit.

• accusation
• allegation
• censure
• charge
• crimination
• impeachment

• assertoric

• “assertion”, in Collins English Dictionary, 2011–present.
• “assertion”, in OneLook Dictionary Search.

• Restainos, airstones, arsonites, asterions, notarises, rai stones, reasonist, senoritas, señoritas

Learned borrowing from Latin assertiō.

• IPA^(key): /a.sɛʁ.sjɔ̃/

• Audio:

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• Audio (France (Vosges)):

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• Audio (France (Lyon)):

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assertion f (plural assertions)

1. assertion

• asserter
• assertif
• assertivement
• assertoire

• “assertion”, in Trésor de la langue française informatisé [Digitized Treasury of the French Language], 2012