1 N-COUNT 自作聪明的人;自以为无所不知的人 If you say that someone is a wise guy, you dislike the fact that they think they are very clever and always have an answer for everything. 自作聪明的人;自以为无所不知的人 [informal, disapproval]

2 N-COUNT 黑手党成员 A wise guy is a member of the Mafia. 黑手党成员 [mainly US, informal]