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• assumption
  assumption

  noun

  something taken for granted; a supposition.
• Assumption
  Assumption

  noun

  the taking up of the Virgin Mary (body and soul) into heaven when her earthly life was ended

assumption

American  

[uh-suhmp-shuhn] / əˈsʌmp ʃən /

noun

• assumptions
  plural

1. something taken for granted; a supposition.

   a correct assumption.

   Synonyms:

   theory, postulate, guess, conjecture, hypothesis, presupposition

2. the act of taking for granted or supposing.

   Synonyms:

   presupposition, presumption

3. the act of taking to or upon oneself.

   Synonyms:

   acceptance

4. the act of taking possession of something.

   the assumption of power.

   Synonyms:

   usurpation, appropriation, seizure

5. arrogance; presumption.

   Synonyms:

   gall, forwardness, effrontery

6. the taking over of another's debts or obligations.

7. Ecclesiastical.

   1. (often initial capital letter) the bodily taking up into heaven of the Virgin Mary.

   2. (initial capital letter) a feast commemorating this, celebrated on August 15.

8. Logic. the minor premise of a syllogism.

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assumption ¹ British  

/ əˈsʌmpʃən /

noun

1. the act of taking something for granted or something that is taken for granted

2. an assuming of power or possession of something

3. arrogance; presumption

4. logic a statement that is used as the premise of a particular argument but may not be otherwise accepted Compare axiom

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Assumption ² British  

/ əˈsʌmpʃən /

noun

1. the taking up of the Virgin Mary (body and soul) into heaven when her earthly life was ended

2. the feast commemorating this, celebrated by Roman Catholics on Aug 15

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Pop Culture

—Assumption persona: A persona is a detailed description of a fictional user (of a product, software program, etc.), based on real-world data. Software engineers and data companies create personas as user models to help build their products. In order to illustrate the utility of using data-driven personas in design, “assumption personas” (personas derived from existing assumptions about users) are used as negative examples showing how assumptions can lead to bad design choices. —Assumption of risk: the name for a defense used in tort law, where the defense argues that the plaintiff took action knowing the risks involved.

Other Word Forms

Derived Forms

• misassumption
  noun
• nonassumption
  noun
• overassumption
  noun
• preassumption
  noun
• reassumption
  noun
• self-assumption
  noun
• superassumption
  noun
• assumptive
  adjective
• assumptively
  adverb

Inflected Forms

Nouns

• assumptions
  plural

Etymology

Origin of assumption

First recorded in 1250–1300; Middle English assumpcioun, assompcioun, assumsion, from Latin assūmptiōn- (stem of assūmptiō ), equivalent to assūmpt(us) “taken up” (past participle of assūmere ) + -iōn- noun suffix; see origin at assume, -ion

Explanation

An assumption is something that you assume to be the case, even without proof. For example, people might make the assumption that you're a nerd if you wear glasses, even though that's not true. Or very nice. From the Latin assumptionem, meaning “a taking or receiving,” assumption was recorded circa 1300 as a noun describing “the reception of the Virgin Mary into heaven.” The word later shook its religious roots and developed into the noun we hear more often today, usually when a person takes something for granted or literally takes possession of something.

Example Sentences

See Examples For:

assumption Assumption assumptions

But the assumption that she should have a stance on issues of the day was nowhere near as strong then.

From Salon ● Aug. 27, 2026

Campaign group Art Not Evidence, which includes lawyers and academics, is lobbying the government to change the law to create an assumption that "creative expression" is not admissible evidence.

From BBC ● Aug. 27, 2026

And it may be the most consequential assumption in the document.

From MarketWatch ● Aug. 26, 2026

The purchase price includes about $4.4 billion in cash, $2 billion in newly issued equity, and the assumption of $575 million of First Eagle notes.

From The Wall Street Journal ● Aug. 26, 2026

Without having discussed it, we both had begun going on the assumption that he would recover.

From "Z for Zachariah" by Robert C. O’Brien

The sanctuary of the Lavra’s Assumption Cathedral sustained a direct hit.

From The Wall Street Journal ● Jun. 15, 2026

Ms. O'Grady received a bachelor's degree in English from Assumption College and an M.B.A. in financial management from Pace University.

From The Wall Street Journal ● Feb. 8, 2026

Canan has been part of Chesney’s staff for more than a decade, starting at Assumption College in 2014 before later following Chesney to Holy Cross, James Madison and now UCLA.

From Los Angeles Times ● Jan. 2, 2026

"Assumption has one of the longest beaches in Seychelles, which is probably one of the most important green turtle nesting beaches in our country," says conservation campaigner Lucie Harter.

From BBC ● Sep. 25, 2025

Assumption had moved from Vernor Highway to a new site on Charlevoix.

From "Middlesex: A Novel" by Jeffrey Eugenides

It resulted from several interdependent factors: unstable defense budgets, overly optimistic assumptions about how long wars will last, shrinking production capacity, and restrictions on allied manufacturing.

From The Wall Street Journal ● Aug. 30, 2026

"This was a good opportunity to go back and go over all of our assumptions - it turns out, yes, we do understand this stuff and we're accounting for it in our cosmology measurement."

From Science Daily ● Aug. 29, 2026

As the luminous, sweet and steel-spined Doralee, she doesn’t just hold her own, she shines, shattering the same sexist assumptions that often plagued Dolly.

From Los Angeles Times ● Aug. 26, 2026

But she still fears people "make assumptions" based on her accent so at networking events she gravitates towards others with a Welsh accent.

From BBC ● Aug. 23, 2026

As they moved from discipline to discipline, the new scientists carried with them a set of assumptions about how to construct new knowledge.

From "The Invention of Science" by David Wootton

Related Words

• acceptance
• belief
• expectation
• guess
• hunch
• hypothesis
• inference
• premise
• presumption
• supposition
• suspicion
• theory