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
The study set strict limits on these possible effects under certain assumptions and improved models of atomic and nuclear behavior.
—
Georgina Jedikovska, Interesting Engineering, 4 Apr. 2026
Investors should consider opportunities in derisked AI businesses where valuations align with long-term underwriting assumptions.
—Matt Witheiler, Fortune, 4 Apr. 2026
Still, with 90% of his customers based in the US, and their assumption that American consumers have the spending power to adopt humanoid robots early, some are willing to pay more for data from US households, even though the hourly wage can be as much as triple that of a worker in Vietnam or India.
—Stephanie Yang, CNN Money, 4 Apr. 2026
The development marks a significant shift from the assumptions that guided the early investigation, which for years centered on the possibility Plante had been abducted.
—Stepheny Price, FOXNews.com, 3 Apr. 2026
See All Example Sentences for assumption
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Georgina Jedikovska, Interesting Engineering, 4 Apr. 2026
Investors should consider opportunities in derisked AI businesses where valuations align with long-term underwriting assumptions.
—Matt Witheiler, Fortune, 4 Apr. 2026
Still, with 90% of his customers based in the US, and their assumption that American consumers have the spending power to adopt humanoid robots early, some are willing to pay more for data from US households, even though the hourly wage can be as much as triple that of a worker in Vietnam or India.
—Stephanie Yang, CNN Money, 4 Apr. 2026
The development marks a significant shift from the assumptions that guided the early investigation, which for years centered on the possibility Plante had been abducted.
—Stepheny Price, FOXNews.com, 3 Apr. 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 5 Apr. 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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