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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

Psychologists call this normalcy bias, which is our mind’s assumption that things will continue as they always have.

From MarketWatch ● Oct. 13, 2026

The tiny creature was found to interpret DNA instructions in a way researchers had never documented before, challenging a long held assumption about how the genetic code works.

From Science Daily ● Oct. 8, 2026

The model assumes that the bird needs the current climate set-up that exists in alpine meadows in the future too, a reasonable but not certain assumption.

From BBC ● Oct. 6, 2026

While that notion may be true for some, it’s not universal, and Iñárritu’s haughty assumption only reflects how disconnected “Digger” is from the very reality it presumes to understand well enough to satirize.

From Salon ● Oct. 5, 2026

This assumption made sense only to those who knew nothing about the company.

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

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

On Friday, as the clock ticked down to the beginning of the talks in Alaska, Ukrainians were celebrating a holy day - the day of the Assumption of the Blessed Virgin Mary.

From BBC ● Aug. 15, 2025

One Sunday in March, she arrived at Assumption before the Divine Liturgy had started.

From "Middlesex: A Novel" by Jeffrey Eugenides

"Its ability to develop increasingly competitive products at lower costs is challenging established assumptions around market share, pricing power and the durability of margins."

From Barron's ● Oct. 13, 2026

"This country in the next decade needs to know where it's going. There are no assumptions here, and as I said, the British public will be the boss of whatever is decided," he said.

From BBC ● Oct. 13, 2026

Read the risk disclosures, projected returns, debt terms, assumptions, fees and conflicts of interest carefully — and pay attention to how long your $350,000 is locked up.

From MarketWatch ● Oct. 12, 2026

The discovery challenges long-standing assumptions about how the eye functions and could eventually lead to new approaches for treating serious conditions that cause blindness.

From Science Daily ● Oct. 11, 2026

It participates in the pathos appeal inasmuch as it stirs an audience’s emotions to laughter—but more importantly, it participates in the ethos appeal, inasmuch as laughter is based on a set of common assumptions.

From "Words Like Loaded Pistols" by Sam Leith

Related Words

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