- the act of supposing
- a fact, theory, etc, that is supposed
WordReference Random House Learner's Dictionary of American English © 2026
sup•po•si•tion /ˌsʌpəˈzɪʃən/USA pronunciation
n.
WordReference Random House Unabridged Dictionary of American English © 2026- an act of supposing:[uncountable]Their accusation is pure supposition on their part.
- something that is supposed;
an assumption:[countable]suppositions about how the money was spent.
sup•po•si•tion
(sup′ə zish′ən),USA pronunciation n.
sup′po•si′tion•al, adj.
sup′po•si′tion•al•ly, adv.
- the act of supposing.
- something that is supposed;
assumption;
hypothesis.
- Latin suppositiōn- (stem of suppositiō) substitution (English meaning by association with suppose), equivalent. to supposit(us) (past participle of suppōnere to substitute) + -iōn- -ion. See sup-, position
- late Middle English 1400–50
sup′po•si′tion•al•ly, adv.
Collins Concise English Dictionary © HarperCollins Publishers::
supposition /ˌsʌpəˈzɪʃən/ n
'supposition' also found in these entries (note: many are not synonyms or translations):
be
- believe
- enough
- even
- historical
- hypothesis
- infer
- reputedly
- speculation
- suppositious
- suppositive
- assumption
- blackacre
- conjecture
- experiment
- fantasy
- guess
- idea
- if
- presumption
- reasonable
- whiteacre
- supposing
- supposititious