'unskillful' originates from the prefix 'un-' meaning 'not' and the word 'skillful', which comes from 'skill', meaning 'ability or expertise'.

'unskillful' changed from the Old English word 'unscylful' and eventually became the modern English word 'unskillful'.

Initially, it meant 'lacking skill or ability', and this meaning has largely remained the same in modern usage.