assertion

noun

as·​ser·​tion ə-ˈsər-shən 

a-

: 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

• declaration
• claim
• insistence
• allegation

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

Slok’s assertion flies in the face of Silicon Valley’s conventional wisdom for the age of AI. —Jake Angelo, Fortune, 28 Apr. 2026

But certainly nothing may have damaged their trust more than the steadfast assertions that the COVID vaccines were able to stop infection and transmission. —Ian Miller Outkick, FOXNews.com, 27 Apr. 2026

Now, those assertions and debates are pretty much a thing of the past. —Lucía Tejo, Glamour, 26 Apr. 2026

But that document raised serious questions about recent assertions made by the city in a related lawsuit. —Alex Riggins, San Diego Union-Tribune, 24 Apr. 2026

Word History

Etymology

see assert

First Known Use

15th century, in the meaning defined above

Phrases Containing assertion

• self-assertion

Rhymes for assertion

• cistercian
• coercion
• desertion
• exertion
• insertion
• mercian
• overexertion
• reassertion

Kids Definition

assertion

noun

as·​ser·​tion ə-ˈsər-shən 

a-

: the act of asserting

also : something asserted : declaration