noun

• (archaic) A mask (cover for the face, used for disguise, protection, etc.)
  "[…] one Roscius Gallus the most excellent player among the Romaines brought up these vizards, which we see at this day used, partly to supply the want of players, when there were moe parts than there were persons, or that it was not thought meet to trouble and pester princes chambers with too many folkes. Now by the chaunge of a vizard one man might play the king and the carter, the old nurse and the yong damsell, the marchant and the souldier or any other part he listed very conveniently."
• (archaic) A visor (part of a helmet covering the face).
  "I walked up gravely to the window in my dusty black coat, and looking through the glass saw all the world in yellow, blue, and green, running at the ring of pleasure.—The old with broken lances, and in helmets which had lost their vizards;—the young in armour bright which shone like gold, beplumed with each gay feather of the east,—all,—all, tilting at it like fascinated knights in tournaments of yore for fame and love.—"
• (archaic, figuratively) Outward appearance; pretense.
  "Oh, that deceit should steal such gentle shapes, And with a virtuous vizard hide foul guile!"