presumption

American  

[pri-zuhmp-shuhn] / prɪˈzʌmp ʃən /

noun

1. the act of presuming.

2. assumption of something as true.

3. belief on reasonable grounds or probable evidence.

4. something that is presumed; an assumption.

5. a ground or reason for presuming or believing.

6. Law. an inference required or permitted by law as to the existence of one fact from proof of the existence of other facts.

7. an assumption, often not fully established, that is taken for granted in some piece of reasoning.

8. unwarrantable, unbecoming, or impertinent boldness.

   Synonyms:

   gall, arrogance, effrontery, audacity

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presumption British  

/ prɪˈzʌmpʃən /

noun

1. the act of presuming

2. bold or insolent behaviour or manners

3. a belief or assumption based on reasonable evidence

4. a ground or basis on which to presume

5. law an inference of the truth of a fact from other facts proved, admitted, or judicially noticed

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Other Word Forms

• overpresumption noun

Etymology

Origin of presumption

1175–1225; Middle English: effrontery, supposition < Latin praesūmptiōn- (stem of praesūmptiō ) anticipation, supposition, Late Latin: presumptuousness, equivalent to praesūmpt ( us ) (past participle of praesūmere to undertake beforehand; presume ) + -iōn- -ion

Explanation

The noun presumption pretty much means jumping to conclusions. It is taking something for granted — an idea, an answer, an event — without having any real knowledge about it, and that is usually not a good thing. Making a presumption means assuming something is true or false without getting all the information necessary for verification. You can decipher this from the prefix pre, which means "before," together with the sume — from the Latin sumere, "to take." Because so many times a presumption turns out to be false, the word has a negative connotation to it; there's something reckless about making up your mind before you know all the facts.

Example Sentences

She wrought real reputational harms and wrecked the presumption of regularity to the point where judges are now just saying: I just assume you lie all the time.

From Slate • Apr. 3, 2026

"It should be noted that the presumption of innocence applies in favour of the accused," the prosecutor's office added.

From BBC • Mar. 28, 2026

“The former defendants in this case, like any other defendant in this situation, still enjoy the presumption of innocence held sacrosanct in our constitutional order,” the judge writes.

From The Wall Street Journal • Feb. 23, 2026

Moira responds to her adult son’s certain presumption that parents are supposed to put their children first with a firm dismissal.

From Salon • Feb. 4, 2026

The presumption in those practice sessions was that he'd be rescuing a crewmate whose tether had broken, but the principle was the same.

From "The Martian" by Andy Weir

Related Words

• assumption
• likelihood
• premise
• supposition
• suspicion