assertion
gb/əsˈɚʃən/ us/əsˈɚʃən/
B2
English
~ 5500
Senses
0 senses
Noun
formal
B2
entity
1
confident claim that something is true
A strong statement that something is true, usually said in a sure and serious way.
Usage pattern:
[someone]'s assertion that [clause]
Common mistake:
Learners sometimes confuse "assertion" with "assumption". An assertion is something you state as true, while an assumption is something you accept as true without proof, often in order to think or talk about a situation. They also sometimes confuse "assertion" (the statement) with "assertiveness" (a personality trait).
Synonyms
claim (Very close in meaning; can sound slightly less formal and is used in a wider range of everyday contexts.)
|
statement (More general and neutral; does not always suggest confidence or possible disagreement.)
|
contention (Similar but often used when the statement is part of a debate or argument.)
Antonyms
denial (Refusal to accept a statement as true; directly opposes an assertion.)
|
question (To doubt or challenge a statement instead of confidently presenting it as true.)
Collocations
make an assertion
|the assertion that [clause]
|unsupported assertion
|bold assertion
|public assertion
|challenge an assertion
Themes
communication
|politics
|law
|core_vocabulary
Examples
- Her assertion that the data was unreliable sparked a heated discussion.
- The company’s assertion that the product is completely safe has been challenged by experts.
- Many people accepted his assertion as fact, even though he gave no evidence.
- The article is built around the central assertion that social media has changed politics.
- I disagree with your assertion that money is the only measure of success.
Learner examples
- His assertion that the food was safe was wrong.
- The writer makes an assertion at the start of the essay.
- I do not accept your assertion that I am late.
- Their assertion that the plan will fail may be true.
- The teacher asked the student to explain his assertion.
Noun
formal
C1
action
2
forceful use or claiming of power/rights
The action of strongly using or claiming power, control, or rights.
Usage pattern:
the assertion of [rights/authority/control]
Common mistake:
Learners may not realize that in phrases like "assertion of rights" the word focuses on the strong, active use or claiming of those rights, not just a simple statement about them.
Synonyms
exercise (Emphasizes actually using power or rights, not just claiming them.)
|
claim (Focuses on saying that you have a right, while "assertion" emphasizes doing this strongly and clearly.)
Antonyms
submission (Accepting another’s power instead of forcefully using your own rights or authority.)
|
relinquishment (Giving up power or rights, the opposite of asserting them.)
Collocations
assertion of rights
|assertion of authority
|assertion of control
|assertion of independence
|assertion of power
Themes
politics
|law
|power
Examples
- The protest was seen as an assertion of citizens’ rights in the face of government pressure.
- Her firm leadership marked a clear assertion of authority in the company.
- The country’s declaration was an open assertion of independence from its former rulers.
- Some view the new law as an assertion of state control over private life.
- The union’s strike was a powerful assertion of workers’ demands.
Learner examples
- The march was an assertion of student power.
- The new leader’s actions were an assertion of control.
- The group made a strong assertion of their rights.
- The war ended with an assertion of national independence.
- The strike was an assertion of the workers’ power.
Noun
technical
C1
entity
3
claimed factual statement in law
In legal cases, a sentence that says a fact is true and is used as part of an argument in court.
Usage pattern:
an assertion in [a complaint / a lawsuit] that [clause]
Common mistake:
Learners may treat "assertion" and "allegation" as completely interchangeable in law. While they overlap, "allegation" often highlights that something is claimed but not proven, whereas "assertion" focuses on the act of firmly stating it as a fact.
Synonyms
allegation (Very close in legal contexts, but "allegation" more strongly suggests that the fact is not yet proven.)
|
claim (A general legal request or demand; "assertion" focuses more on the specific stated fact.)
Antonyms
concession (Admitting a fact instead of asserting a different one in your favor.)
|
retraction (Taking back a previously made assertion.)
Collocations
legal assertion
|factual assertion
|false assertion
|unsupported assertion
|assertion in the complaint
Themes
law
|communication
Examples
- The court found that his assertion of self‑defense was not supported by the evidence.
- The complaint includes the assertion that the company knew about the defects.
- Her lawyer’s key assertion is that the contract was never legally valid.
- The judge questioned the factual basis of the witness’s assertion.
- The jury must decide whether the plaintiff’s central assertion is credible.
Learner examples
- The lawyer made an assertion that the car was unsafe.
- The judge did not accept the man’s assertion of self‑defense.
- In the complaint, there is an assertion that the company lied.
- The court looks carefully at each assertion of fact.
- Her legal assertion was not supported by any document.
Noun
technical
C1
entity
4
programming check that a condition holds
In programming, a special line of code that checks if something is true while the program is running and stops or shows an error if it is not true.
Usage pattern:
an assertion that [condition] must hold
Common mistake:
Learners sometimes confuse the everyday meaning of "assertion" (a strong statement in words) with its technical meaning in programming. In code, an assertion is an active check that can stop the program, not just a comment or note.
Synonyms
check (A very general term; an assertion is a specific kind of check that usually stops the program when it fails.)
|
guard (In code, a condition that protects against bad input; an assertion is a stronger, often debugging‑oriented version.)
Antonyms
assumption (An unstated belief that something is true; an assertion explicitly tests and enforces the condition instead of silently assuming it.)
Collocations
add assertions
|assertion failure
|assertion error
|debug assertion
|runtime assertion
Themes
technology
|programming
Examples
- The developer added an assertion to ensure the index is never negative.
- When the input was empty, the program crashed with an assertion failure.
- Assertions are useful for catching logic errors early in the development process.
- The test framework raises an assertion if the expected value is not returned.
- They removed most runtime assertions before releasing the production build.
Learner examples
- The code uses an assertion to check the value.
- If the condition is false, the assertion stops the program.
- Assertions help the programmer find bugs.
- We add an assertion so the number cannot be less than zero.
- The test fails when the assertion is not true.
Grammar
Dictionary form
assertion
IPA
GB/əsˈɚʃən/
US/əsˈɚʃən/
Syllables & stress
as - ser - tion (3 syllables)
Stress on 2nd syllable (ser)
Word forms
Noun
- Base: assertion
- Plural: assertion, assertions
Word family
Expressions
assertion of rights
1/əsˈɚʃən əv ɹˈaɪts/
fixed phrase
formal
strong use or claim of rights
strong action to use or claim your legal or moral rights
Examples
- The protest was an assertion of rights by the local community.
- Freedom of speech includes the assertion of rights that some may find uncomfortable.
- The lawyer framed the case as an assertion of rights, not just a financial dispute.
challenge an assertion
1/t͡ʃˈælɪnd͡ʒ ən əsˈɚʃən/
fixed phrase
question or dispute a claim
to say that a strong statement may be wrong and ask for proof or correction
Examples
- Several scientists publicly challenged the minister’s assertion about climate data.
- No one in the meeting dared to challenge her assertion.
- Students are encouraged to challenge assertions that are not clearly explained.
make an assertion
1/mˈeɪk ən əsˈɚʃən/
fixed phrase
formal
state something confidently as true
to say clearly and strongly that something is true
Examples
- Before you make an assertion like that, you should check the facts.
- The scientist was careful not to make an assertion that went beyond the data.
- He often makes sweeping assertions without any evidence.
the assertion that
1/ðə əsˈɚʃən ðˈæt/
fixed phrase
formal
phrase introducing a stated claim
words used before a clause to talk about a strong statement, for example "the assertion that the plan will work"
Examples
- The report questions the assertion that the policy will reduce crime.
- Many experts reject the assertion that violent games cause real‑world violence.
- We found no support for the assertion that the drug is completely safe.
unsupported assertion
1/ʌnsəpˈɔɹtɪd əsˈɚʃən/
fixed phrase
formal
claim made without supporting evidence
a strong statement that is not backed by facts or proof
Examples
- The article is full of unsupported assertions and emotional language.
- Any unsupported assertion in an academic paper should be removed or referenced.
- His criticism was dismissed as an unsupported assertion.