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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

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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

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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

Nowak said the notion of adding 8 gigawatts of capacity a year is a reasonable assumption, so the key question is monetization per incremental watt.

From MarketWatch ● Oct. 30, 2026

This assumption has become an important part of modern cosmology, supporting the view that the universe looks broadly similar when observed from different locations on sufficiently large scales.

From Science Daily ● Oct. 29, 2026

The new research suggests that this assumption may need to change.

From Science Daily ● Oct. 29, 2026

Moody’s left the rating unchanged on the assumption that France successfully adopts a deficit-reducing budget for 2027.

From The Wall Street Journal ● Oct. 26, 2026

Eventually he let me go on the assumption that I was some wayward orphan, because what mother would send her ten-year-old child to jail?

From "Born a Crime: Stories from a South African Childhood" by Trevor Noah

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

Many think the Assumption row could help sweep Dr Herminie to power, as he campaigns to clean up politics and rid public administration of corruption.

From BBC ● Sep. 25, 2025

Meanwhile, on Hurlbut, Father Stylianopoulos, head priest of Assumption Greek Orthodox Church, has finally come over to bless the house.

From "Middlesex: A Novel" by Jeffrey Eugenides

"He is going to be frank with the British people about what the trade-offs are but no assumptions have been made on that."

From BBC ● Oct. 27, 2026

It is, Moe points out, “to incorporate more conservative assumptions about how the market may price underlying fundamentals.”

From MarketWatch ● Oct. 26, 2026

Nonetheless, Pavlovic wrote, the Serbian students’ success “challenges conventional assumptions about the resources necessary to defeat an entrenched incumbent” and will become the subject of scholarly research.

From Los Angeles Times ● Oct. 26, 2026

Using an advanced 3D imaging technique, the team was able to see deep inside the crystal for the first time, revealing hidden features that challenge decades of scientific assumptions.

From Science Daily ● Oct. 25, 2026

He calculated that the Earth was 89 million years old–an age that fit neatly enough with Kelvin’s assumptions but unfortunately not with reality.

From "A Short History of Nearly Everything" by Bill Bryson

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Related Words

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

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