Jump To:

• 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.

---

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

---

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

---

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

For much of the past few years, the main assumption had been that “all money spent on artificial intelligence was well spent,” Sosnick said.

From MarketWatch ● Nov. 3, 2026

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 of large-scale uniformity plays a central role in how scientists reconstruct the universe's history.

From Science Daily ● Oct. 29, 2026

A new film by Jimmy Chin and Elizabeth Chai Vasarhelyi, Everest: The Other Side, pitches that assumption off the mountaintop.

From The Wall Street Journal ● Oct. 29, 2026

Everyone always makes this assumption, but in my case it didn't pan out.

From "Americanized" by Sara Saedi

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

India was keen to build a military base on Assumption but was rebuffed.

From BBC ● Sep. 25, 2025

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

From "Middlesex: A Novel" by Jeffrey Eugenides

But they’re only as useful as their assumptions are correct.

From MarketWatch ● Oct. 29, 2026

Greater collaboration would let investors assess their portfolios, test their assumptions and estimate a social money multiplier.

From The Wall Street Journal ● Oct. 28, 2026

"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

Scientists exploring the forests of Yunnan, China, have discovered an extraordinary giant fungus that is challenging previous assumptions about how large certain fungi can grow.

From Science Daily ● Oct. 26, 2026

As an outsider, he learns to see the world more clearly, because he can’t afford the luxuries of assumptions or illusions.

From "The Mona Lisa Vanishes" by Nicholas Day

Random Word

Spin the wheel and learn a new word!

---

Related Words

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

---