'unregistered' originates from the prefix 'un-' meaning 'not' and the word 'register' from Latin 'registrare', where 'reg-' meant 'rule' and 'str-' meant 'to write'.

'registrare' transformed into the Old French word 'register', and eventually became the modern English word 'register'.

Initially, it meant 'to write in a list or record', but over time it evolved into its current meaning of 'not officially recorded'.