Bull's-eye \bull's"-eye`\, n.

1. (Naut.) A small circular or oval wooden block without sheaves, having a groove around it and a hole through it, used for connecting rigging
2. A small round cloud, with a ruddy center, supposed by sailors to portend a storm
3. A small thick disk of glass inserted in a deck, roof, floor, ship's side, etc., to let in light
4. A circular or oval opening for air or light
5. A lantern, with a thick glass lens on one side for concentrating the light on any object; also, the lens itself. --Dickens
6. (Astron.) Aldebaran, a bright star in the eye of Taurus or the Bull
7. (Archery & Gun.) The center of a target
8. A thick knob or protuberance left on glass by the end of the pipe through which it was blown
9. A small and thick old-fashioned watch. [Colloq.]
10. (Optics) Bull's-eye condenser, or Bull's-eye, a lens of short focal distance used for concentrating rays of light