'underworld' originates from Old English, specifically the word 'underweorold', where 'under' meant 'beneath' and 'weorold' meant 'world'.

'underweorold' transformed into the Middle English word 'underwerld', and eventually became the modern English word 'underworld'.

Initially, it meant 'the world beneath the earth', but over time it evolved into its current meanings of 'realm of the dead' and 'criminal society'.