supposition

noun

sup·​po·​si·​tion ˌsə-pə-ˈzi-shən 

1

: something that is supposed : hypothesis

2

: the act of supposing

suppositional

ˌsə-pə-ˈzi-sh(ə-)nəl 

adjective

Synonyms

• hypothesis
• theory
• thesis
• proposition

Examples of supposition in a Sentence

a supposition that proved correct

This is just idle supposition.

Recent Examples on the Web

O'Donnell took further issue with her feeling that Hasselbeck didn't defend her against suppositions that O'Donnell was un-American for her opposition to military advances. —Joey Nolfi, Entertainment Weekly, 7 Oct. 2025

Slavik knocked Combs for lining up speaking engagements for as soon as next week with the supposition that he’d be released. —Nicki Brown, CNN Money, 4 Oct. 2025

One of the big suppositions behind the big data center boom is that the most cutting edge AI models will be at least as large, if not larger, than the leading models that exist today. —Jeremy Kahn, Fortune, 3 Sep. 2025

That kind of supposition is for amateurs. —Sherry Kuehl, Kansas City Star, 6 Aug. 2025

Word History

Etymology

Middle English supposicioun, from Anglo-French supposicion, from Late Latin supposition-, suppositio, from Latin, act of placing beneath, from supponere

First Known Use

15th century, in the meaning defined at sense 1

Phrases Containing supposition

• on the supposition that

Rhymes for supposition

• abolition
• acquisition
• admonition
• ammunition
• apparition
• apposition
• coalition
• competition
• composition
• definition
• deglutition
• demolition

Kids Definition

supposition

noun

sup·​po·​si·​tion ˌsəp-ə-ˈzish-ən 

1

: something that is supposed

2

: the act of supposing

suppositional

-ˈzish-nəl 

-ən-ᵊl

adjective