From Middle English besmorchen (attested in besmorchid). Compare Middle English bismotered (“bespattered, soiled”). By surface analysis, be- +‎ smirch.

• (Received Pronunciation) IPA^(key): /bɪˈsmɜːtʃ/
• (General American) IPA^(key): /bɪˈsmɝːt͡ʃ/

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• Rhymes: -ɜː(ɹ)tʃ

besmirch (third-person singular simple present besmirches, present participle besmirching, simple past and past participle besmirched)

1. (transitive, literary) To make dirty.

   Synonyms: soil, sully, tarnish; see also Thesaurus:dirty

2. (transitive) To tarnish something, especially someone's reputation.

   Synonyms: blacken, debase, libel, smear, slander; see also Thesaurus:defame

   Antonym: unbesmirch

   The newspaper was on a campaign to besmirch the actor.

   • 1599 (date written), William Shakespeare, “The Life of Henry the Fift”, in Mr. William Shakespeares Comedies, Histories, & Tragedies[…] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, →OCLC, (please specify the act number in uppercase Roman numerals, and the scene number in lowercase Roman numerals):

     Our gayness and our gilt are all besmirch'd
     With rainy marching in the painful field

   • 1850, Nathaniel Hawthorne, The Scarlet Letter, a Romance, Boston, Mass.: Ticknor, Reed, and Fields, →OCLC:

     "It may be," he replied, "because I will not encounter the dishonor that besmirches the husband of a faithless woman.[…]"

   • 1928, Edgar Rice Burroughs, Tarzan, Lord of the Jungle:

     Sir Guy might still have slain him without besmirching his knightly honor

• Schembri