blinker

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.

Whatever obstructs sight or discernment.

The eyelid.

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.

To put blinkers on.

“The farmer stopped to blinker his horse before riding into an area of heavy traffic.”