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 Cincinnati was awarded the event based on the assumption that it would be played at Riverfront Stadium. Mark Schmetzer,, "Rockin' the Riverfront: It was a bumpy road en route to Riverfront Stadium construction," 16 May 2020 Ahmaud Arbery seems to be the only one who was presumed to be a criminal and ultimately the only one murdered based on that assumption. USA TODAY, "Security video from construction site may show Ahmaud Arbery was getting water, lawyer says," 15 May 2020 Robin Robinson, who led the Biomedical Advanced Research and Development Authority from 2008 to 2016, said the agency has spent billions of dollars building up vaccine production capacity in the United States based on that assumption. Helen Branswell, STAT, "Mounting promises on Covid-19 vaccines are fueling false expectations, experts say," 6 May 2020 These passes would let people move around and return to work—based on the assumption that possession of such antibodies prevents reinfection. The Economist, "Covid-19 Leaving lockdown means understanding immune responses to the virus," 2 May 2020 However, that policy decision rests on the assumption that the respective party leaders will make qualified appointments within their respective parties. Jake Curtis, National Review, "A Dubious Appointment to the Wisconsin Ethics Commission," 1 May 2020 Her plan appears to be predicated on the assumption that his sister has the fallback — in the event of Saul's death, Dorit hands over his most sensitive intelligence. Seija Rankin,, "Homeland series finale recap: Goodbye to you, America," 27 Apr. 2020 With coronavirus sweeping the country, President Donald Trump suggesting that Americans might want to disinfect their veins and Joe Biden going underground, such an assumption would appear reasonable. The Economist, "Election monitoring We spent the lockdown sorting American voters into 380,000 distinct groups," 2 May 2020 And that staggering figure was compiled with the assumption that the state’s stay-at-home order would be lifted by June 1. Breanna Edwards, Essence, "California Could See $6.7 Billion In Losses Over 2 Years Due To Coronavirus," 26 Apr. 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

19 May 2020

Cite this Entry

“Assumption.” Dictionary, Merriam-Webster, Accessed 25 May. 2020.

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More Definitions for assumption


How to pronounce assumption (audio)

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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