Source : WordNet®

bull's eye
     n 1: in target shooting: a score made by hitting the center of
          the target; "in repeated sets of five shots his numbers
          of bull's-eyes varied"
     2: the center of a target [syn: {bull}]
     3: something that exactly succeeds in achieving its goal; "the
        new advertising campaign was a bell ringer"; "scored a
        bull's eye"; "hit the mark"; "the president's speech was a
        home run" [syn: {bell ringer}, {mark}, {home run}]