'unaccounted' originates from the prefix 'un-' meaning 'not' and the word 'accounted' from the verb 'account', which comes from Old French 'acont' meaning 'to count or reckon'.

'Accounted' changed from the Old French word 'acont' and eventually became the modern English word 'account'.

Initially, it meant 'to count or reckon', but over time it evolved into its current meaning of 'not included in calculations or records'.