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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

Segura said that assumption couldn’t be further from the truth and that the former couple had been recording separate episodes since they split earlier this year.

From Los Angeles Times ● Aug. 13, 2026

"Our research shows that this assumption may not always hold true. Other treponemal diseases may also have been transmitted from mother to child."

From Science Daily ● Aug. 12, 2026

She said the group had long been advocating "for an end to the automatic assumption that someone in their home or private life is a potential customer."

From BBC ● Aug. 11, 2026

One key assumption for target-date funds is that an investor’s time horizon ends around age 60, at which point the portfolio shifts to a safer mix of stocks and bonds to preserve assets for retirement.

From MarketWatch ● Aug. 7, 2026

“What is your assumption about home prices, and what is your assumption about loan losses.”

From "The Big Short" by Michael Lewis

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

"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

So the lease of Assumption Island, or at least part of it, to the Qatari royal family has stirred sensitivities.

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

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

Spending four formative years in a community where hundreds of services are collectively financed and individually consumed can shape assumptions about how institutions function and how resources should be allocated.

From The Wall Street Journal ● Aug. 14, 2026

This finding calls into question long-established assumptions about fertility.

From Science Daily ● Aug. 6, 2026

People take a look at her and make assumptions.

From Los Angeles Times ● Aug. 6, 2026

And what a shame that her assumptions had proven correct!

From "Orphan Train" by Christina Baker Kline

Related Words

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