To remove a mask from someone's face; to reveal someone's true identity or intentions.
From 'dis-' plus 'mask' (from Italian 'maschera' or Spanish 'máscara', ultimately of uncertain origin, possibly from Arabic). The word has been used since the 16th century in both literal and metaphorical senses.
Shakespeare used 'dismask' to mean revealing hidden truths, and it became popular in mystery novels. Today's internet culture of 'unmasking' internet trolls is literally the same idea—removing the 'mask' that lets people hide their true selves online.
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