1. to prevent from growing 2. to be able to digest food instead of vomiting while you're ill. 3. not to make noise 4. to prevent people from being successful
keep down
Examples
1. Helen needs to keep her weight down. 2. After food poisoning I wasn't able to keep anything down for a week. 3. Can you keep the music down, please? 4. A lot of talented people were kept down that time.