'unscrupulous' originates from Latin, specifically the word 'scrupulus,' where 'scrupulus' meant 'a small sharp stone' or 'a source of uneasiness.'

'scrupulus' transformed into the English word 'scruple,' and eventually became the modern English word 'unscrupulous' by adding the prefix 'un-' to indicate the absence of scruples.

Initially, it meant 'without scruples or moral hesitation,' and this meaning has largely remained the same in modern usage.