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
That assumption suppresses accountability.
—
Michael Fealey, Sportico.com, 14 Feb. 2026
Along with this comes a lack of awareness about eating disorders, stigma and unhealthy attitudes and assumptions toward mental health from coaches and other athletic personnel, all of which can impede an athlete’s likelihood of seeking care.
—Emily Hemendinger, The Conversation, 13 Feb. 2026
To my eye, Zurek has almost tied up the loose ends that have been confounding physics for 100 years, without invoking any substantially new or speculative assumptions.
—Quanta Magazine, 13 Feb. 2026
These experiences deepen understanding, challenge assumptions, and help students connect Connecticut’s past and present in a more meaningful way.
—Letters To The Editor, Hartford Courant, 13 Feb. 2026
See All Example Sentences for assumption
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Michael Fealey, Sportico.com, 14 Feb. 2026
Along with this comes a lack of awareness about eating disorders, stigma and unhealthy attitudes and assumptions toward mental health from coaches and other athletic personnel, all of which can impede an athlete’s likelihood of seeking care.
—Emily Hemendinger, The Conversation, 13 Feb. 2026
To my eye, Zurek has almost tied up the loose ends that have been confounding physics for 100 years, without invoking any substantially new or speculative assumptions.
—Quanta Magazine, 13 Feb. 2026
These experiences deepen understanding, challenge assumptions, and help students connect Connecticut’s past and present in a more meaningful way.
—Letters To The Editor, Hartford Courant, 13 Feb. 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 18 Feb. 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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