means A covering for the face, worn to conceal identity, protect, disguise, or perform — or, figuratively, any false front put up to hide one's true feelings.

from From French 'masque', borrowed in the 1500s, which came from Italian 'maschera' or 'mascara'. Beyond that the trail forks: one likely root is Medieval Latin 'masca', meaning a witch, spectre, or nightmare — a thing that haunts the face. Some trace it further to Arabic 'maskharah', a buffoon or object of ridicule, from a verb meaning 'to mock'. Either way, the word was born tangled up with deception, performance, and things that aren't what they seem.