smirch

transitive verb

1. to make dirty or discolor as by smearing or staining with grime
2. to sully or dishonor (a reputation, good name, etc.)

Origin: ME smorchen, prob. < OFr esmorcher, to hurt < es- (< L ex), intens. + pp. of mordre, to bite, hurt: see mordant

noun

1. a smudge; smear; stain
2. a stain on a reputation, etc.