'underhanded' originates from the combination of 'under' and 'hand,' where 'under' meant 'beneath' and 'hand' referred to 'control or power.'

'underhanded' evolved from the Old English word 'underhænd,' which meant 'secretly or deceitfully,' and eventually became the modern English word 'underhanded.'

Initially, it meant 'done secretly or deceitfully,' and this meaning has largely remained the same in modern usage.