Proposition and Supposition

Proposition

Proposition noun - An idea that is the starting point for making a case or conducting an investigation.
Usage example: started the discussion with the simple proposition that no one ever does anything out of pure altruism

Supposition is a synonym for proposition in conjecture topic. In some cases you can use "Supposition" instead a noun "Proposition", when it comes to topics like assumption.

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

Proposition is a synonym for supposition in conjecture topic. You can use "Proposition" instead a noun "Supposition".

How words are described

ridiculous ridiculous proposition ridiculous supposition
Cite this Source
Supposition and Proposition. (2016). Retrieved 2026, July 21, from https://thesaurus.plus/related/proposition/supposition
Proposition & Supposition. N.p., 2016. Web. 21 Jul. 2026. <https://thesaurus.plus/related/proposition/supposition>.
Supposition or Proposition. 2016. Accessed July 21, 2026. https://thesaurus.plus/related/proposition/supposition.
Google Ngram Viewer shows how "proposition" and "supposition" have occurred on timeline