noun

a small mark or flaw which spoils the appearance of something.

the girl’s hands were without a blemish

imperfection,fault,flaw,defect,deformity,discoloration,disfigurement,bruise,scar,pit,pockmark,pock,scratch,dent,chip,notch,nick,line,score,cut,incision,gash,mark,streak,spot,fleck,dot,blot,stain,smear,patch,trace,speck,speckle,blotch,smudge,smut,smirch,fingermark,fingerprint,impression,imprint,marking,blaze,stripe,birthmark,splotch,splodge,stigma

verb

spoil the appearance or quality of (something).

his reign as world champion has been blemished by controversy

mar,spoil,impair,disfigure,blight,deface,flaw,mark,spot,speckle,blotch,discolour,scar,ruin,destroy,wreck,be a blot on the landscape,disfeature,sully,tarnish,besmirch,blacken,smirch,stain,blot,taint,soil,befoul,dirty,disgrace,damage,defame,calumniate,injure,harm,hurt,undermine,debase,degrade,denigrate,dishonour,stigmatize,drag through the mud,vitiate