'non-' originates from Latin, specifically the word 'non', where 'non' meant 'not'; 'tarnish' originates from Old French, specifically the word 'tarnir', where 'tarnir' meant 'to make dark or soil'.

'tarnish' changed from Old French 'tarnir' to Middle English 'tarnishen' and eventually became the modern English word 'tarnish'. The negative prefix 'non-' was adopted into Modern English usage to form compounds such as 'non-tarnishing'.

Initially, 'tarnish' meant 'to make dark or soil'; over time it evolved to mean 'to lose luster or become discolored (especially by oxidation)'. 'Non-tarnishing' therefore came to mean 'not undergoing that loss of luster or discoloration'.