Why is the ninth month called September?
in the figurative sense, 1867, from horses wearing blinkers to limit the range of their vision (see blinker).
1630s, "one who blinks," agent noun from blink (v.). As a type of horse eye screen to keep the animal looking straight ahead, from 1789. Slang meaning "the eye" is from 1816. Meaning "intermittent flashing light" is from 1923.