1. （头盔上的）面罩，面甲，护面
    A visor is a movable part of a helmet which can be pulled down to protect a person's eyes or face.

2. （汽车内挡风玻璃上方的）遮阳板
    A visor is a piece of plastic or other material fixed above the windscreen inside a car, which can be turned down to protect the driver's eyes from bright sunshine.

1. a brim that projects to the front to shade the eyes

    e.g. he pulled down the bill of his cap and trudged ahead

    Synonym: billpeakeyeshadevizor

2. a piece of armor plate (with eye slits) fixed or hinged to a medieval helmet to protect the face

    Synonym: vizor