'unnoticed' originates from the prefix 'un-' meaning 'not' and the word 'notice,' which comes from Latin 'notitia,' meaning 'a being known.'

'notitia' transformed into the Old French word 'notice,' and eventually became the modern English word 'notice.' The prefix 'un-' was added to form 'unnoticed.'

Initially, 'notice' meant 'to know or be aware of something,' and 'unnoticed' evolved to mean 'not being aware of or seeing something.'