Definition of SUPPOSITION

an idea that is the starting point for making a case or conducting an investigation <my supposition is that this grape variety, which flourishes in southern France, should do equally well here, given the similar climate>
an opinion or judgment based on little or no evidence <it's pure supposition on your part that there's something illegal going on next door>
something taken as being true or factual and used as a starting point for a course of action or reasoning <worthless genetic research that was based on the erroneous supposition that acquired characteristics can be passed on to offspring>

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