bull's-eye (Noun) — A lantern with a single opening and a sliding panel that can be closed to conceal the light.
bull's-eye (Noun) — In target shooting: a score made by hitting the centre of the target.
bull's-eye (Noun) — The centre of a target.
bull's-eye (Noun) — Something that exactly succeeds in achieving its goal. ex. "scored a bull's eye"