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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

"Everyone's challenges are different. But you can't make the assumption that the person with high support needs is always having a harder time. They will in some regards, but not in all."

From BBC ● Aug. 21, 2026

“It’s on its side and the mirror image. So it runs backwards to what would be sort of a logical assumption of its threading pattern.”

From Los Angeles Times ● Aug. 20, 2026

The assumption was built into the feature: We have already begun shopping for you.

From Salon ● Aug. 20, 2026

The lender advanced the money on the assumption that a GPU will still find a renter after the contract that paid for it expires, no matter what model is popular then.

From MarketWatch ● Aug. 20, 2026

Henry Lee, for example, apprised Madison that the assumption debate reminded him of those glorious days of yesteryear, when the Virginia Assembly refused to recognize Parliament’s right to tax colonies.

From "Founding Brothers: The Revolutionary Generation" by Joseph J. Ellis

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

For some, the Assumption Island deal looks like one broken promise too many.

From BBC ● Sep. 25, 2025

Only the stained glass windows remain intact inside the sturdy facade of St Mary's of the Assumption on the far edge of Chicago's South Side.

From BBC ● May 8, 2025

Brother Daniel was talking of the last moment we knew of in Mary’s human life, her Assumption.

From "In the Time of the Butterflies" by Julia Alvarez

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

Researchers at Monash University have predicted an unusual new form of quantum matter that could overturn long-held assumptions about how ultracold particles behave.

From Science Daily ● Aug. 21, 2026

Moving beyond capacity assumptions, Nowak believes the “swing factor” determining the company’s growth will come down to how the company can monetize each watt of compute.

From MarketWatch ● Aug. 17, 2026

The world of “Lanterns” prefers to be bracingly honest about our false assumptions about heroism and whether the people we deem to be noble really are.

From Salon ● Aug. 14, 2026

“Yeah. You don’t want people to make assumptions about me.”

From "On the Come Up" by Angie Thomas

Related Words

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