'Visor' definitions:

Definition of 'visor'

noun

A piece of armor plate (with eye slits) fixed or hinged to a medieval helmet to protect the face [syn: visor, vizor]

noun

A brim that projects to the front to shade the eyes; "he pulled down the bill of his cap and trudged ahead" [syn: bill, peak, eyeshade, visor, vizor]

From: GCIDE

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. [1913 Webster]
2. A mask used to disfigure or disguise. "My very visor began to assume life." --Shak. [1913 Webster]
My weaker government since, makes you pull off the visor. --Sir P. Sidney. [1913 Webster]
3. The fore piece of a cap, projecting over, and protecting the eyes. [1913 Webster]