'dim-witted' originates from the combination of 'dim,' meaning 'not bright,' and 'wit,' meaning 'mental sharpness.'

'dim-witted' evolved from the Middle English word 'dim' and the Old English word 'witt,' eventually forming the modern English word 'dim-witted.'

Initially, it meant 'lacking brightness in wit,' and this meaning has largely remained the same in modern usage.