1. hypothesis: something that it is suggested might be true, or that is accepted as true on the basis of some evidence but without proof That seems a reasonable supposition on the basis of his previous behavior.
2. mental act of supposing: the mental act of supposing something to be the case, or ideas that result from supposing, especially as opposed to ideas based on firm evidence All this is mere supposition.
[Late 16th century. Directly or via French< Latin supposition-< supposit-, past participle of supponere "place under" < ponere "to place"]
