assertion

noun

as·​ser·​tion ə-ˈsər-shən How to pronounce assertion (audio)
a-
Synonyms of assertion
: the act of asserting or something that is asserted: such as
a
: insistent and positive affirming, maintaining, or defending (as of a right or attribute)
an assertion of ownership/innocence
b
: a declaration that something is the case
He presented no evidence to support his assertions.

Synonyms of assertion

Relevance
See All Synonyms & Antonyms in Thesaurus

Examples of assertion in a Sentence

the assertion that all men have certain unalienable rights is set forth in the Declaration of Independence made the unlikely assertion that gravity affects light
Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
The battle — which escalated into a federal lawsuit filed Thursday by the Justice Department against the state, Secretary of State Shirley Weber and Logan — features striking assertions of official misconduct. — Kevin Rector, Los Angeles Times, 17 Oct. 2026 Data from container shipping market analysis firm Linerlytica supports the assertion of a traffic increase. — Glenn Taylor, Footwear News, 14 Oct. 2026 The Ohio facility at the center of the rumor debunked the assertion. — Elizabeth Robinson, NBC news, 13 Oct. 2026 The defense also pushed Cheever on her assertion that Birchmore was not suicidal. — Kristina Rex, CBS News, 13 Oct. 2026 See All Example Sentences for assertion

Word History

Etymology

see assert

First Known Use

15th century, in the meaning defined above

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

Phrases Containing assertion

Rhymes for assertion

See All Rhymes for assertion

Browse Nearby Words

assertible
assertion
assertional
See all Nearby Words

Cite this Entry

“Assertion.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/assertion. Accessed 20 Oct. 2026.

Copy Citation

Kids Definition

assertion

noun
as·​ser·​tion ə-ˈsər-shən How to pronounce assertion (audio)
a-
: the act of asserting
also : something asserted : declaration

More from Merriam-Webster on assertion

Britannica.com: Encyclopedia article about assertion

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

Last Updated: - Updated example sentences

More from Merriam-Webster

Word of the Day

Listen to the pronunciation of compunction

See Definitions and Examples »

Popular in Grammar & Usage

See More

Merriam-Webster’s Great Big List of Words You Love to Hate

'Can' vs. 'May'

'Affect' vs. 'Effect'

More Commonly Mispronounced Words

Is it 'nerve-racking' or 'nerve-wracking'?
See More

Popular in Wordplay

See More

The Longest Long Words List

9 Words That Sound Like Insults But Aren't

Did 'orange' the fruit or the color come first?

Even More Bird Names that Sound Like Insults (and Sometimes Are)

12 Lovely and Unusual Words for the Natural World
See More

Popular

See More

Merriam-Webster’s Great Big List of Words You Love to Hate

The Longest Long Words List

9 Words That Sound Like Insults But Aren't
See More

Games & Quizzes

See All
Play Quordle: Guess all four words in a limited number of tries. Each of your guesses must be a real 5-letter word.
Quordle Can you solve 4 words at once?
Play Blossom: Solve today's spelling word game by finding as many words as you can using just 7 letters. Longer words score more points.
Blossom Pick the best words!
Play Missing Letter: a crossword with a twist. Each of the 25 puzzle words start with a different letter of the alphabet. Which letter is missing?
The Missing Letter A daily crossword with a twist
artwork of illustrated limes with the text limes and smile with an arrow connecting the two words
Quiz: Spot the Anagram! Scramble these words to find new words with the e...
See All