Dull or discolored due to oxidation or dirt, losing shine or luster; or morally or reputationally damaged or spoiled.
From Old French 'ternir,' meaning to make dull or dim. The word comes from Germanic roots meaning to turn dark, and evolved to describe both physical and reputational damage.
Silver tarnish is literally the metal reacting with sulfur in the air to form silver sulfide—it's not dirt, it's a chemical reaction—which is why you can't just wash it off; you need actual chemistry to fix it.
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