tarnish

To dull the luster of; discolor, especially by exposure to air or dirt.

To detract from or spoil.

To bring disgrace to; sully.

To lose luster; become discolored.

To become less enjoyable or estimable.

The condition of being tarnished.

A film or layer of discoloration on a metal surface caused by corrosion or oxidation.

The condition of being disgraced or made less estimable.

To diminish or destroy the luster of; sully; dull: used of an alteration induced by the air, or by dust or dampness; also, in mineralogy, to change the natural color or luster of the surface of: said chiefly of the metallic minerals. See tarnish, n., 2.