'unselfish' originates from the prefix 'un-' meaning 'not' and the word 'selfish', where 'self' meant 'one's own person' and '-ish' meant 'having the nature of'.

'unselfish' was formed by adding the prefix 'un-' to the word 'selfish', which was derived from Middle English 'self' and the suffix '-ish'.

Initially, it meant 'not selfish', and this meaning has largely remained the same in modern usage.