assumption
noun
as·sump·tion
ə-ˈsəm(p)-shən 
1
: a taking to or upon oneself
the assumption of a new position
2
: the act of laying claim to or taking possession of something
the assumption of power
3
a
: an assuming that something is true
a mistaken assumption
b
: a fact or statement (such as a proposition, axiom (see axiom sense 2), postulate, or notion) taken for granted
4
a
: the taking up of a person into heaven
b
Assumption
: August 15 observed in commemoration of the Assumption of the Virgin Mary
5
: the taking over of another's debts
6
Synonyms of assumption
Examples of assumption in a Sentence
I made the assumption that he was coming, so I was surprised when he didn't show up.
He will come home tomorrow. At least, that's my assumption.
Many scientific assumptions about Mars were wrong.
I'm telling you our arrival time on the assumption that you will check to see whether or not our flight is on time before you come to the airport.
Her plan is based on the underlying assumption that the economy will improve in the near future.
her assumption of the presidency
the buyer's assumption of debt
Recent Examples on the Web
Scientists design experiments to break their assumptions, because that’s where real discovery happens.
—
Stefan Pollack, Forbes.com, 18 June 2026
That challenges our previous assumption that plague spillover was a side effect of people taking up farming and settling in permanent villages and towns, living closer to each other and to an assortment of animals (and their fleas).
—ArsTechnica, 18 June 2026
When Ryan Jones had to have surgery just before the playoffs began to repair a broken hamate bone in his right wrist, the natural assumption was that St. Rita would be without him for the rest of the way.
—Steve Millar, Chicago Tribune, 11 June 2026
The working assumption — correctly — is that anything digital taken into China should be treated as potentially compromised.
—Emma Bussey, FOXNews.com, 11 June 2026
See All Example Sentences for assumption
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Stefan Pollack, Forbes.com, 18 June 2026
That challenges our previous assumption that plague spillover was a side effect of people taking up farming and settling in permanent villages and towns, living closer to each other and to an assortment of animals (and their fleas).
—ArsTechnica, 18 June 2026
When Ryan Jones had to have surgery just before the playoffs began to repair a broken hamate bone in his right wrist, the natural assumption was that St. Rita would be without him for the rest of the way.
—Steve Millar, Chicago Tribune, 11 June 2026
The working assumption — correctly — is that anything digital taken into China should be treated as potentially compromised.
—Emma Bussey, FOXNews.com, 11 June 2026
See All Example Sentences for assumption
Cite this Entry
“Assumption.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/assumption. Accessed 19 Jun. 2026.
Copy CitationKids Definition
assumption
noun
as·sump·tion
ə-ˈsəm(p)-shən
1
capitalized
: August 15 observed as a church festival to mark the taking up of the Virgin Mary into heaven
2
a
: the act of taking upon oneself or taking possession of something
3
a
: the belief that something is true
b
: a fact or statement taken for granted
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