'supposed' originates from Latin, specifically the word 'supponere,' where 'sub-' meant 'under' and 'ponere' meant 'to place.'

'supponere' transformed into the Old French word 'supposer,' and eventually became the modern English word 'suppose' through Middle English.

Initially, it meant 'to place under,' but over time it evolved into its current meaning of 'to assume or believe something without proof.'