Supposition and Speculation

Supposition

Supposition noun - An idea that is the starting point for making a case or conducting an investigation.
Usage example: my supposition is that this grape variety, which flourishes in southern France, should do equally well here, given the similar climate

Speculation is a synonym for supposition in belief topic. In some cases you can use "Speculation" instead a noun "Supposition", when it comes to topics like opinion, conjecture, assumption, guess. popular alternative

Speculation

Speculation noun - A message expressing an opinion based on incomplete evidence.

Supposition is a synonym for speculation in theory topic. You can use "Supposition" instead a noun "Speculation", if it concerns topics such as conjecture, opinion, assumption, hypothesis. popular alternative

How words are described

common common supposition common speculation
real real supposition real speculation
off-the-wall off-the-wall supposition off-the-wall speculation
Cite this Source
Speculation and Supposition. (2016). Retrieved 2026, July 21, from https://thesaurus.plus/related/supposition/speculation
Supposition & Speculation. N.p., 2016. Web. 21 Jul. 2026. <https://thesaurus.plus/related/supposition/speculation>.
Speculation or Supposition. 2016. Accessed July 21, 2026. https://thesaurus.plus/related/supposition/speculation.
Google Ngram Viewer shows how "supposition" and "speculation" have occurred on timeline