1. Anatomy The small, circular, optically insensitive region in the retina where fibers of the optic nerve emerge from the eyeball. It has no rods or cones. Also called optic disk.

2. An area that one cannot see because of an obstruction.

3. An area where radio reception is weak or nonexistent.

4. A subject about which one is markedly ignorant or prejudiced: His niece is his blind spot; in his eyes, she can do no wrong.