- Oxidation or discoloration, especially of a decorative metal exposed to air.
- (intransitive) To oxidize or discolor due to oxidation.
"Careful storage of silver will prevent it from tarnishing."
- (intransitive, figuratively) To lose its lustre or attraction; to become dull.
- (transitive) To soil, sully, damage or compromise
"He is afraid that he will tarnish his reputation if he disagrees."