Definitions

1. noun

a person who speaks or acts in a silly or annoyingly knowing way, often to provoke a reaction.

“After a while, he became a wiseacre in the group, constantly making snide comments.”

2. verb

to talk or act in a silly or annoyingly knowing way, often to provoke a reaction.

“Stop being such a wiseacre and let someone else have a turn to talk.”