Anything that blinks, such as the turn signal of an automobile.
Eye shields attached to a hood for horses, to prevent them from seeing backwards and partially sideways.
A black eye.
In Conway's Game of Life, an arrangement of three cells in a row that switches between horizontal and vertical orientations in each generation.
The eyelid.
Whatever obstructs sight or discernment.
To put blinkers on.
An international distress signal used by shipping and aircraft.