'unindebted' originates from the prefix 'un-' meaning 'not' and the word 'indebted', which comes from the Old French 'endetté', derived from Latin 'indebitatus', where 'in-' meant 'in' and 'debitum' meant 'debt'.

'indebted' changed from the Old French word 'endetté' and eventually became the modern English word 'indebted'. The prefix 'un-' was added to form 'unindebted'.

Initially, 'indebted' meant 'in debt', but with the prefix 'un-', it evolved to mean 'not in debt'.