'uncontaminated' originates from the prefix 'un-' meaning 'not' and the word 'contaminated', which comes from Latin 'contaminatus', meaning 'made impure'.

'contaminatus' transformed into the English word 'contaminate', and with the addition of the prefix 'un-', it became 'uncontaminated'.

Initially, it meant 'not made impure', and this meaning has largely remained the same in modern usage.