Assumption
Assumption noun - Something taken as being true or factual and used as a starting point for a course of action or reasoning.
Idea
Idea noun - Something imagined or pictured in the mind.
Usage example: my idea of the perfect vacation spot is an uncrowded, unspoiled beach
Assumption is a synonym for idea in sense topic. Sometimes you can use "Assumption" instead a noun "Idea".
Mutual synonyms
How words are described
| good | good assumption | good idea |
| best | best assumption | best idea |
| similar | similar assumption | similar idea |
| common | common assumption | common idea |
| Other adjectives: original, initial, reasonable, fair, simple, poor, popular, brilliant, big, wrong, dangerous, bad, false, decent, personal, traditional, general, above, odd, basic, central. | ||
Both words in one sentence
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In Metal Gear Solid, Otacon designed Metal Gear REX under the assumption that it would be used as a mobile TMD to destroy incoming missiles - he had no idea that his employers would arm it with nukes instead.
Source: Ignorance Is Bliss -
Rocket Raccoon escapes and rescues the others, because the Collector's idea of his perfect world was based on the assumption that he was actually a raccoon.
Source: Lotus-Eater Machine -
It's not just the assumption of diva-dom, but the Brawn Hilda trope is so ubiquitous that the uninitiated often have the idea that a high BMI is somehow necessary for the voice.
Source: Acceptable Professional Targets
Cite this Source
Idea and Assumption. (2016). Retrieved 2026, August 16, from https://thesaurus.plus/related/assumption/idea
Assumption & Idea. N.p., 2016. Web. 16 Aug. 2026. <https://thesaurus.plus/related/assumption/idea>.
Idea or Assumption. 2016. Accessed August 16, 2026. https://thesaurus.plus/related/assumption/idea.
Google Ngram Viewer shows how "assumption" and "idea" have occurred on timeline