Also found in: Dictionary, Thesaurus, Medical, Legal, Encyclopedia.
To talk back to someone in a rude, impertinent, and disrespectful manner. You're going to get suspended again if you keep smarting off to your teachers like that. I heard that the boss fired him because he smarted off during a board meeting.
To speak or act impertinently: One of my coworkers smarted off to the management and was fired. If you smart off in class, the teacher will punish you.