VISOR (also spelled viser, vizor, vizard or visard)  , a term now used generally of the various forms of movable face-guards in the helmet of medieval and later times . It meant properly a mask for the face, and is an adaptation of the O.Fr. visiere, mod. visiere, as is seen by the M.E. forms viser, visere . It is thus to be referred to the Fr. vis, face, Lat. visus, from videre, to see . In this sense the word " visor " is modern, the movable guard for the upper part of the face being known as an " aventail " or " ventail," and that foi' the lower part a " beaver " (see HELMET) .