be ‧ smirch /bɪˈsmɜːtʃ $ -ɜːrtʃ/ BrE AmE verb [transitive]
[ Date: 1600-1700 ; Origin: smirch 'to make dirty' (15-20 centuries) , perhaps from Old French esmorcher 'to torture' ]
literary besmirch sb’s honour/reputation to spoil the good opinion that people have of someone