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 of supposition

• 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

What becomes alarmingly evident through the key assumptions check is how many of the current responses expect a quick resolution of the conflict — a supposition that is unsound, or at least unsupported. —Judd Devermont, semafor.com, 27 Apr. 2026

Zlotnikov wrote that the condition was likely caused by a mutation that had occurred very early in embryonic development, a supposition that was confirmed decades later by genetic analysis. —Jerome Groopman, New Yorker, 6 Apr. 2026

The past eight months have exposed both suppositions. —Liam Twomey, New York Times, 11 Mar. 2026

As Jackie herself once reminded John, a Kennedy has no choice but to accept that the press and public will speculate, interpret, exaggerate, and invent notions about them based on their own suppositions. —Rafaela Bassili, Vulture, 27 Feb. 2026

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