v. 1. To begin; appear. Rain came on toward morning. He felt a cold coming on. 2. To grow or do well; thrive. The wheat was coming on. His business came on splendidly. 3. or come upon . To meet accidentally; encounter; find. He came on an old friend that day when he visited his club. He came upon an interesting idea in reading about the French Revolution.
Synonym: COME ACROSS, HAPPEN ON. 4. informal Let's get started; let's get going; don't delay; don't wait. Used as a command. "Come on, or we'll he late," said Joe, but Lou still waited. 5. informal Please do it! Used in begging someone to do something. Sing us just one song, Jane, come on! Come on, Laura, you can tell me. I won't tell anybody.