'declassify' originates from the prefix 'de-' meaning 'remove' and 'classify' from Latin 'classificare', where 'classis' meant 'class' and 'facere' meant 'to make'.

'declassify' changed from the Latin word 'classificare' and eventually became the modern English word 'declassify'.

Initially, it meant 'to remove from a class or category', but over time it evolved into its current meaning of 'to remove the classification of secrecy'.