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

Based on her recent accessory choice, these are all safe assumptions. Vogue, "Gigi Hadid Revives a Granny Accessory," 24 Apr. 2019 Aside from the foundational work, there are some interesting assumptions that are required to make this plan work in the long run. David Hansen,, "Laguna Beach tries to map out its cultural mojo," 10 July 2018 The only piece of it is the assumption that the runner would be at second base. Nick Moyle, Houston Chronicle, "Nolan Kingham carries UT past TCU in series opener," 18 May 2018 Each new report is damaging the most essential part of the MoviePass brand: the assumption that the service will stay in operation in some form, and that new subscribers will be able to get their money’s worth. Bryan Bishop, The Verge, "Today’s SEC filing suggests MoviePass’ time is running out," 8 May 2018 Read More Past Marty Hurney drafts offer clues to Panthers' selection strategy That may not be a true assumption — Hurney likes to wheel and deal and did so in almost every draft from 2002-12 in his first stint as Carolina’s GM. Scott Fowler, charlotteobserver, "What needs should Panthers fill in first 88 selections? A road map for Marty Hurney | Charlotte Observer," 25 Apr. 2018 Full moons are revelatory, so save your assumptions for another day. Randon Rosenbohm, Allure, "What May’s Taurus Horoscope Means for You," 30 Apr. 2019 Until the bombshell in season seven’s finale, when it was revealed that Jon Snow is actually a Targaryen and therefore the rightful heir to the throne, audiences have operated under the assumption that Daenerys was the real heir. Jill Gutowitz, Glamour, "Daenerys Targaryen Will Sit on the Iron Throne on Game of Thrones, and You Know It," 12 Apr. 2019 But with her new Netflix movie Cam, a collaboration with her director friend Daniel Goldhaber, Mazzei's hoping to challenge that assumption. Carl Kelsch, Marie Claire, "'Cam' Is the Sex-Positive Horror Movie You Have to See," 24 Dec. 2018

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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Statistics for assumption

Last Updated

20 May 2019

Look-up Popularity

Time Traveler for assumption

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

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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

What made you want to look up assumption? Please tell us where you read or heard it (including the quote, if possible).


to speak slightingly about or to degrade

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