assumption

UK: 'assumption', 'Assumption': /əˈsʌmpʃən/

US: /əˈsʌmpʃən/

US: (ə sump′shən)

WordReference Random House Unabridged Dictionary of American English © 2025

as•sump•tion  (ə sump′shən), n. 

1. something taken for granted;
   a supposition:
   a correct assumption.
2. the act of taking for granted or supposing.
3. the act of taking to or upon oneself.
4. the act of taking possession of something:
   the assumption of power.
5. arrogance;
   presumption.
6. the taking over of another's debts or obligations.
7. [Eccles.]
   • (often cap.) the bodily taking up into heaven of the Virgin Mary.
   • (cap.) a feast commemorating this, celebrated on August 15.

• Latin assūmptiōn- (stem of assūmptiō), equivalent. to assūmpt(us) taken up (past participle of assūmere; see assume) + -iōn- -ion
• Middle English assumpcioun, assompcioun, assumsion 1250–1300

Synonyms

• 1, 2. presupposition.
• 1. hypothesis, conjecture, guess, postulate, theory.
• 3. presumption.
• 5. effrontery, forwardness.

Collins Concise English Dictionary © HarperCollins Publishers::

assumption / 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. a statement that is used as the premise of a particular argument but may not be otherwise accepted
   Compare axiom4

Etymology: 13th Century: from Latin assūmptiō a taking up, from assūmere to assume

asˈsumptive adjective

WordReference Random House Learner's Dictionary of American English © 2025

as•sume /əˈsum/   v. [~ + object] , -sumed, -sum•ing. 

1. to take for granted without proof; suppose:
   to assume that everyone wants peace.
2. to take upon oneself:
   to assume responsibility.
3. to take over the duties or responsibilities of:
   to assume the office of treasurer.
4. to pretend to have or be;
   feign:
   to assume a humble manner.

as•sump•tion /əˈsʌmpʃən/  n. [countable* uncountable] See -sum-.

WordReference Random House Unabridged Dictionary of American English © 2025

as•sume  (ə so̅o̅m′), v.t., -sumed, -sum•ing. 

1. to take for granted or without proof;
   suppose;
   postulate;
   posit:
   to assume that everyone wants peace.
2. to take upon oneself;
   undertake:
   to assume an obligation.
3. to take over the duties or responsibilities of:
   to assume the office of treasurer.
4. to take on (a particular character, quality, mode of life, etc.);
   adopt:
   He assumed the style of an aggressive go-getter.
5. to take on;
   be invested or endowed with:
   The situation assumed a threatening character.
6. to pretend to have or be;
   feign:
   to assume a humble manner.
7. to appropriate or arrogate;
   seize;
   usurp:
   to assume a right to oneself; to assume control.
8. to take upon oneself (the debts or obligations of another).
9. [Archaic.] to take into relation or association;
   adopt.

v.i. 

10. to take something for granted;
    presume.

• Latin assūmere to take to, adopt, equivalent. to as- as- + sūmere to take up; see consume
• Anglo-French assumer)
• late Middle English (1400–50

as•sum′er, n. 
Synonyms

• 1. presuppose.
• 6. See pretend. 

Collins Concise English Dictionary © HarperCollins Publishers::

Assumption / 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