Open English Wordnet
Nouns
(n)bull's eyein 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”
(n)bell ringer, bull's eye, mark, home runsomething 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”