Having one's reputation damaged or honor stained; soiled in reputation or character.
From besmirch plus the past participle suffix -ed, which creates both past tense and adjective forms in English.
Besmirched is alive and well in modern English, particularly in legal and political language—'his reputation was besmirched' feels weightier than 'his reputation was damaged.' It persists because it evokes both literal dirt and moral corruption simultaneously.
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