A visor is a surface that protects the eyes

Eye protection

Eye protection is protective gear for the eyes, which comes in many types depending upon the threat that is to be reduced. The threats can be particles, light, wind blast, heat, sea spray or some type of ball or puck used in sports...

, such as shading them from the sun or other bright light or protecting them from objects.

Nowadays many visors are transparent, but before strong transparent substances such as polycarbonate

Polycarbonate

PolycarbonatePhysical PropertiesDensity 1.20–1.22 g/cm3Abbe number 34.0Refractive index 1.584–1.586FlammabilityV0-V2Limiting oxygen index25–27%Water absorption – Equilibrium0.16–0.35%Water absorption – over 24 hours0.1%...

 were invented, visors were opaque like a mask

Mask

A mask is an article normally worn on the face, typically for protection, disguise, performance or entertainment. Masks have been used since antiquity for both ceremonial and practical purposes...

 with small holes to see and breathe through, such as:

• The part of a helmet
  Visor (armor)
  A visor was used in conjunction with some Medieval war helmets such as the bascinet. The visor usually consisted of a hinged piece of steel that contained openings for breathing and vision. Visors protected the face during battle. Most knights or warriors who wore visors usually were spotted on...
  
   in a suit of armor that protects the eyes.
• A type of hat
  Sports Visor
  A sports visor — also called a sun visor or visor cap — is a type of crownless hat consisting simply of a visor or brim with a strap encircling the head...
  
   consisting only of a visor and a way to fasten it to the head.
• Any such vertical surface on any hat or helmet.
• Any such horizontal surface on any hat or helmet (called a peak
  Peaked cap
  A peaked cap, forage cap, barracks cover, or combination cap is a form of headgear worn by the armed forces of many nations and also by many uniformed civilian organizations such as law enforcement agencies...
  
  in British English
  British English
  British English, or English , is the broad term used to distinguish the forms of the English language used in the United Kingdom from forms used elsewhere...
  
  ).
• A device in an automobile
  Automobile
  An automobile, autocar, motor car or car is a wheeled motor vehicle used for transporting passengers, which also carries its own engine or motor...
  
   that the driver or front passenger can lower over part of the windshield
  Windshield
  The windshield or windscreen of an aircraft, car, bus, motorbike or tram is the front window. Modern windshields are generally made of laminated safety glass, a type of treated glass, which consists of two curved sheets of glass with a plastic layer laminated between them for safety, and are glued...
  
   to block the sun (sun visor
  Sun visor
  A sun visor is a component of an automobile located on the interior just above the windshield .Most cars have two sun visors, one for the driver's side and a second for the passenger's side, with the rear-view mirror often mounted in between the two sun visors. Each visor can be lowered to help...
  
  ).

Some modern devices called visors are similar, for example:

• Visor (ice hockey)

Types of modern transparent visors include:

• The transparent or semi-transparent front part of a motorcycle crash helmet
  Motorcycle helmet
  A motorcycle helmet is a type of protective headgear used by motorcycle riders. The primary goal of a motorcycle helmet is motorcycle safety - to protect the rider's head during impact, thus preventing or reducing head injury or saving the rider's life...
  
   or police riotsquad helmet
  Riotsquad helmet
  A riot protection helmet is a type of helmet designed for law enforcement and military use to protect its wearer's head, face and eyes from handheld melee weapons, and thrown projectiles such as bricks, as may be met in riot control...
  
  s
  • Safety faceshields
    Face shield
    A face shield is a device used to protect wearer's entire face from impact hazard such as flying objects and road debris, chemical splashes , or potentially infectious fluid .-Industry:...
    
     for construction-type applications
• An eyeshield
  Eyeshield
  An eyeshield is a piece of football equipment. It is a visor that attaches to the helmet of a player to protect the eyes. It leaves the mouth exposed and covers the eyes and nose. Only clear eyeshields are allowed in high school football. On the college level, a clear eyeshield may be used if the...
  
   to protect the eyes from sunlight on an American football helmet
• A shield to protect the eyes from sunlight on a flight helmet
• Green eyeshade
  Green eyeshade
  Green eyeshades are a type of visor that were worn most often from the late 19th century to the middle 20th century by accountants, telegraphers, copy editors and others engaged in vision-intensive, detail-oriented occupations in order to lessen eyestrain and other effects of early incandescent...
  
  s, formerly worn by accountants and others engaged in vision-intensive, detail-oriented occupations

The word vizard (sometimes visard) is used in Shakespearean English

Early Modern English

Early Modern English is the stage of the English language used from about the end of the Middle English period to 1650. Thus, the first edition of the King James Bible and the works of William Shakespeare both belong to the late phase of Early Modern English...

 to refer to a visor, a mask

Mask

A mask is an article normally worn on the face, typically for protection, disguise, performance or entertainment. Masks have been used since antiquity for both ceremonial and practical purposes...

, or a disguise

Disguise

A disguise can be anything which conceals or changes a person's physical appearance, including a wig, glasses, makeup, costume or other ways. Camouflage is one type of disguise for people, animals and objects...

(ex. "There, then, that vizard, that superfluous case, that hid the worse and show'd the better face." -- Love's Labors Lost V.ii.387)