1. verb To respond to an insult or criticism, sometimes in a vengeful manner. She calmly clapped back at critics by asserting that her weight is none of their business. I'm not proud of it, but I did clap back at the girl who stole my boyfriend by starting a vicious rumor about her.
2. noun A response to an insult or criticism, sometimes in a vengeful manner. I'm not great at the clap back because I get easily flustered by criticism. Her clap back was a vicious rumor targeting the girl that stole her boyfriend.