assumptions

IPA/əˈsʌmp.ʃən/
KK[əsˈʌmpʃənz]IPA/əˈsʌmp.ʃən/

assumptions — noun

  • assumptionssingular
  • assumptionsesplural

1. a belief that is treated as correct without requiring proof; accepted as a start

1.nounB2
Definition

a belief that is treated as correct without requiring proof; accepted as a starting point for decisions or reasoning even though it has not been firmly established.

Example

Esteban made the assumption that everyone had already eaten, so he did not order extra food.

make + assumption + that-clause

Many of our daily decisions are based on untested assumptions about how people will behave.

passive: are based on + assumption

Common collocations
  • make an assumption
  • based on an assumption
  • rest on an assumption
  • challenge an assumption
  • false assumption
  • underlying assumption
  • reasonable assumption
  • assumption about
Synonyms
  • presumption

    similar meaning but often implies an assumption made with some degree of confidence, sometimes before evidence is considered

  • supposition

    a more formal word for something assumed to be true, often as a basis for reasoning

  • belief

    broader term; a belief may be supported by evidence or faith, whereas an assumption is taken for granted without proof

  • guess

    much less formal and suggests little supporting evidence at all

Antonyms
  • fact

    something known to be true through evidence or observation

  • certainty

    a fact or belief that is beyond doubt

Grammar Patterns

make + assumption + (that-clause)

assumption + about + noun

Usage Note

Frequently paired with 'make', 'base on', 'rest on', or 'challenge'. The that-clause structure (make the assumption that...) is very common in academic and professional writing.

Common Mistakes

I assumed that the shop is open.' (present tense in the clause after a past main verb).
I assumed that the shop was open.
the clause verb should agree with the past-tense main verb in formal English.
I made an assumption of he is honest.
I made the assumption that he is honest.
use a that-clause, not a prepositional phrase with 'of'.

2. the act of beginning to have power, control, or responsibility for something; th

2.nounC1
Definition

the act of beginning to have power, control, or responsibility for something; the taking on of a duty, role, or position.

Example

The assumption of the presidency brought with it a heavy set of security responsibilities.

assumption of [role/position]

Ziad's assumption of the team leadership was welcomed by everyone in the department.

Common collocations
  • assumption of office
  • assumption of power
  • assumption of responsibility
  • assumption of liability
  • assumption of duty
  • upon the assumption of
Synonyms
  • taking on

    less formal; used in everyday contexts for accepting duties

  • acceptance

    emphasises agreement to take on a role or responsibility

  • undertaking

    formal, emphasising the start of a significant task or duty

Antonyms

Grammar Patterns

assumption + of + noun

Usage Note

Used almost exclusively in formal, legal, or official contexts. The noun 'assumption' is followed by 'of' and a role or obligation (assumption of office, assumption of duty, assumption of debt). Distinguish from Sense 1: this sense describes the act of taking something on, not believing something without proof.

Common Mistakes

His assumption as manager was last month.
His assumption of the manager role was last month.
use 'of' not 'as' after this sense of 'assumption'.

3. behaviour that is too confident or proud, showing that you believe you have a ri

3.nounC1
Definition

behaviour that is too confident or proud, showing that you believe you have a right to something you do not actually deserve; presumptuousness.

Example

The new intern spoke with such assumption that the senior staff were offended.

with assumption — adverb-like phrase showing manner

Ramón criticised his colleague's assumption in acting as though she already ran the department.

Common collocations
  • with assumption
  • air of assumption
  • assumption in doing something
Synonyms
  • presumptuousness

    more direct synonym; behaviour that oversteps proper boundaries

  • arrogance

    broader term for an offensive sense of superiority

  • audacity

    boldness that shows a lack of respect, often with a stronger nuance of daring

Antonyms
  • humility

    modest behaviour, the opposite of arrogant assumption

  • modesty

    not claiming or drawing attention to oneself

Grammar Patterns

with assumption — used as an adverb-like noun phrase

Usage Note

This sense carries a negative, critical tone. It appears in formal writing or disapproving descriptions. Unlike Sense 1 and 2, it is uncountable and is not used with the 'make an assumption' pattern. Distinguish from Sense 1 by context: here the focus is on offensively confident behaviour, not on a belief.

Common Mistakes

He made an assumption that he could interrupt.' (when meaning arrogant behaviour).
He acted with assumption, interrupting everyone.
this sense uses 'with assumption' as a manner adverbial, not 'make an assumption'.

Word family

Synonym discussion

Sense: noun/1

All four words refer to an idea held without full proof, but they differ in formality, strength of confidence, and context. 'Assumption' is the broadest and most common — it describes something taken for granted, often as a starting point for reasoning ('the assumption that prices will rise'). 'Presumption' adds a note of confidence: it is an assumption made with some belief that it is true, sometimes before evidence is examined ('the presumption of innocence'). 'Supposition' is more formal and provisional, suggesting a belief held as a basis for argument without strong conviction ('on the supposition that funds are available'). 'Hypothesis' is a technical, scientific term for a proposed explanation tested through experimentation ('the hypothesis was confirmed by the data'). 'Guess' is informal and suggests little evidence. A learner might say 'I made a guess about the answer' but would use 'I started from the assumption that...' in an academic essay.

presumptionsupposition ↗hypothesis ↗guess ↗

Common collocations

Nouns

Adverbs

Phrases

  • on the assumption that
  • based on the assumption
  • under the assumption
  • assumption of risk
  • challenge the assumption

Prepositions

Etymology

LatinFrenchEnglish

'Assumption' comes from Latin 'assumptio' (a taking up), from 'assumere' (to take to oneself — from 'ad-' + 'sumere' meaning 'to take'). The word entered Middle English through Old French 'assumpcion', originally used in religious contexts (the taking up of the Virgin Mary into heaven). From the 15th century, it developed the secular senses: first the act of taking on a role or duty (Sense 2), then the logical sense of accepting a proposition as a premise without proof (Sense 1, recorded from the 16th century), and finally the pejorative sense of presumptuous conduct (Sense 3, from the 17th century).

First known use

13th century

13th century, in the meaning defined at sense 4a