as·​sump·​tion | \ ə-ˈsəm(p)-shən How to pronounce assumption (audio) \

Definition of assumption

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
3a : 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
4a : the taking up of a person into heaven
b capitalized : August 15 observed in commemoration of the Assumption of the Virgin Mary
5 : the taking over of another's debts

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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
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Recent Examples on the Web Yet in spite of all that, my teacher’s first reaction to meeting him was to make this weird, offensive assumption about him and my mom. San Diego Union-Tribune, "Column: Quit stereotyping Black fathers and using them as a scapegoat for society’s failures," 26 Feb. 2021 That assumption isn't completely unfounded, and dancing trends are alive and well on the platform. Brennan Long, Southern Living, "5 Reasons Southerners Should Join the Fun on TikTok," 24 Feb. 2021 But when the couple picked up Hopper, a French bulldog puppy, last February, that assumption was almost immediately challenged. New York Times, "The People Who Got Puppies Were in Over Their Heads," 19 Feb. 2021 Now remote work has unleashed a fiscal crisis across BART, Muni and Caltrain and thrown that assumption into disarray. Roland Li, San Francisco Chronicle, "Downtown San Francisco is reeling. More remote work could add to the pain," 15 Feb. 2021 That assumption was based on several generalizations about the inner solar system’s evolution. Quanta Magazine, "Rumbles on Mars Raise Hopes of Underground Magma Flows," 1 Feb. 2021 That assumption has now been called into doubt, and the government’s handling of the mink cull is haunting the country’s leadership — in more ways than one. Washington Post, "After Denmark’s mink cull, questions over legality, science and what to do with ‘zombie minks’," 18 Dec. 2020 The study also assumes that the smaller animal and microbial biomass fraction has remained constant through time, but that assumption might not be borne out by future investigations. Maddie Stone, Environment, "Human-made materials now equal weight of all life on Earth," 9 Dec. 2020 Many investors expect the two sides to strike a deal, which leaves the currency vulnerable to any setbacks that could upend that assumption. William Shaw,, "Pound Falls as Investors Question Progress in Brexit Trade Talks," 6 Dec. 2020

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'assumption.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of assumption

13th century, in the meaning defined at sense 4a

History and Etymology for assumption

Middle English, from Late Latin assumption-, assumptio taking up, from Latin assumere — see assume

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Time Traveler for assumption

Time Traveler

The first known use of assumption was in the 13th century

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Statistics for assumption

Last Updated

1 Mar 2021

Cite this Entry

“Assumption.” Dictionary, Merriam-Webster, Accessed 3 Mar. 2021.

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More Definitions for assumption



English Language Learners Definition of assumption

: something that is believed to be true or probably true but that is not known to be true : something that is assumed
: the act of beginning a role, duty, etc.
: the act of taking or beginning to have power, control, etc., in a job or situation


as·​sump·​tion | \ ə-ˈsəmp-shən How to pronounce assumption (audio) \

Kids Definition of assumption

1 : the act of taking on the assumption of power
2 : something accepted as true I'm making plans on the assumption that you will be here.

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Comments on assumption

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