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
And in November, a Sacramento Superior Court judge ordered the utility to stop providing details on customers’ electricity usage to law enforcement agencies in most cases, after a 2022 lawsuit alleged that the data sharing led to false assumptions about customers’ activities.
—
Sacbee.com, 9 Jan. 2026
As the video spread, viewers flooded the comments with advice, concern and assumptions about her daily life.
—Ashley Vega, PEOPLE, 8 Jan. 2026
The initiative’s drafters question the assumption that millionaires invariably move from high- to low-tax jurisdictions, citing several studies, including one from 2016 based on IRS statistics showing that elites are generally unwilling to move to exploit tax advantages across state lines.
—Business Columnist, Los Angeles Times, 8 Jan. 2026
But that assumption is deeply flawed, if not dangerous, particularly for Iranians who hope for meaningful political change.
—Sanam Vakil, Time, 8 Jan. 2026
See All Example Sentences for assumption
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Cite this Entry
“Assumption.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/assumption. Accessed 13 Jan. 2026.
Kids 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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