The Collaborative International Dictionary of English v.0.48:

Visor \Vis"or\, n. [OE. visere, F. visi[`e]re, fr. OF. vis. See
   Visage, Vision.] [Written also visar, visard,
   vizard, and vizor.]
   1. A part of a helmet, arranged so as to lift or open, and so
      show the face. The openings for seeing and breathing are
      generally in it.
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   2. A mask used to disfigure or disguise. "My very visor began
      to assume life." --Shak.
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            My weaker government since, makes you pull off the
            visor.                                --Sir P.
                                                  Sidney.
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   3. The fore piece of a cap, projecting over, and protecting
      the eyes.
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The Collaborative International Dictionary of English v.0.48:

Vizard \Viz"ard\, n. [See Visor.]
   A mask; a visor. [Archaic] "A grotesque vizard." --Sir W.
   Scott.
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         To mislead and betray them under the vizard of law.
                                                  --Milton.
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