'unpleasantly' originates from the word 'unpleasant', which is derived from the prefix 'un-' meaning 'not' and 'pleasant', which comes from the Latin word 'placere', meaning 'to please'.

'unpleasant' changed from the Old French word 'plaisant', which meant 'pleasing', and eventually became the modern English word 'unpleasant' by adding the prefix 'un-'.

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