Tarnish

Noun

 * 1) Oxidation or discoloration, especially of a decorative metal exposed to air.

Verb

 * 1) To oxidize or discolor due to oxidation.
 * Careful storage of silver will prevent it from tarnishing.
 * 1) To soil, sully, damage or compromise
 * He is afraid that he will tarnish his reputation if he disagrees.

Thesaurus
achromatize, asperse, aspersion, attaint, badge of infamy, bar sinister, baton, bedaub, befoul, begrime, benasty, bend sinister, besmear, besmirch, besmoke, besoil, bespatter, bestain, black eye, black mark, blacken, blanch, bleach, blemish, bloodstain, blot, blotch, blow upon, blur, brand, broad arrow, call names, calumniate, censure, champain, contaminate, corrupt, dab, damage, darken, daub, debase, decolor, decolorize, defame, defile, degrade, denigrate, dim, dirty, disapprove, discolor, disgrace, dishonor, disparage, disparagement, drain, drain of color, dull, embarrass, engage in personalities, etiolate, expose, expose to infamy, eyesore, fade, fleck, flick, flyspeck, foul, fume, gibbet, grime, hang in effigy, harm, heap dirt upon, hurt, impair, imputation, infect, injure, macula, maculation, macule, mar, mark, mark of Cain, mess, mess up, muckrake, muddy, nasty, onus, pale, patch, peroxide, pillory, pillorying, point champain, pollute, prejudice, reflection, reprimand, reproach, revile, ruin, scorch, sear, singe, slander, slubber, slur, smear, smirch, smoke, smooch, smouch, smudge, smut, smutch, soil, spatter, speck, speckle, splash, splatter, splotch, spoil, spot, stain, stigma, stigmatism, stigmatization, stigmatize, sully, taint, tar, throw mud at, tone down, vilify, vitiate, wash out, whiten

Etymology
From ternir:, stem of ternir:, from  ternir:, of  origin, from  *undefined:, from, from. Cognate with *undefined:, tarnen: (Modern German tarnen:),  dyrnan:, diernan:. More at,.