sup·​po·​si·​tion | \ˌsə-pə-ˈzi-shən \

Definition of supposition 

1 : something that is supposed : hypothesis

2 : the act of supposing

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Other Words from supposition

suppositional \ˌsə-​pə-​ˈzish-​nəl, -​ˈzi-​shə-​nᵊl \ adjective

Synonyms for supposition


hypothesis, proposition, theory, thesis

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Examples of supposition in a Sentence

a supposition that proved correct This is just idle supposition.

Recent Examples on the Web

No one knows, but after years of supposition and pie-in-the-sky conjecture from planners and passengers alike, BART officials are starting to study a second Transbay Tube. Michael Cabanatuan, San Francisco Chronicle, "BART gets serious about a 2nd East Bay-S.F. Transbay Tube," 21 Feb. 2018 These suppositions are unduly charitable toward Makan Delrahim, the department’s antitrust chief. Holman W. Jenkins, WSJ, "Why an Antitrust Farce Must Continue," 13 July 2018 This was a completely baseless supposition and the child of a mind blinded by love. Steve Donoghue, The Christian Science Monitor, "3 books for deep summer reading," 6 July 2018 The supposition is that someone casually fingering a strategically bland Theory oxford shirt one minute may then get entranced by the flamboyant prints beaming out of the Valentino section. New York Times, "Nordstrom Men: Choose Your Own Adventure," 9 May 2018 But that supposition is contradicted by his business history and by his natural impulsiveness — perhaps his defining characteristic — which often wins out over rationality. Benjamin Hart, Daily Intelligencer, "Chill Out on the Whole Mueller Getting Fired Thing, Republicans Say," 10 Apr. 2018 That's a complete supposition, but this gets weirder by the day. Fox News, "Secretary Nielsen talks immigration, relationship with Trump," 15 May 2018 One obvious problem in blaming social media for miserable young people is the supposition that there has ever been a halcyon time for teenagers. Fortune, "How Smartphones and Social Media Can Steal Childhood," 8 May 2018 Of course, this was always a ridiculous supposition by Trump: Mueller is leading a criminal probe and will go wherever the evidence leads. Chris Cillizza, CNN, "John Dowd's resignation tells you a lot about Donald Trump's mindset," 22 Mar. 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'supposition.' 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 supposition

15th century, in the meaning defined at sense 1

History and Etymology for supposition

Middle English supposicioun, from Anglo-French supposicion, from Late Latin supposition-, suppositio, from Latin, act of placing beneath, from supponere

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Last Updated

21 Oct 2018

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Time Traveler for supposition

The first known use of supposition was in the 15th century

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English Language Learners Definition of supposition

: an idea or theory that you believe is true even though you do not have proof

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Comments on supposition

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


a nest or breeding place

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