mid-13c., "deprive of honor, disgrace," from Old French deshonorer (12c.), from Medieval Latin dishonorare (reformed from classical Latin dehonestare), from dis- "opposite of" (see dis-) + honorare "to honor," from honor "honor, dignity, office, reputation," which is of unknown origin. Related: Dishonored; dishonoring.
c. 1300, "want of honor in conduct; state of being disgraced; a violation of one's honor or dignity," from Old French deshonor (12c., Modern French déshonneur), from deshonorer (see dishonor (v.)). Meaning "a cause or source of shame" is from 1550s.