1. Add more of something, especially in an excessive or burdensome way
   "The teacher piled on extra homework before the holiday"
    
2. Join others in criticizing or attacking someone
   "The media piled on with accusations after the scandal broke"
    
3. (of people) jump on top of someone in a group, typically in celebration
   "The team piled on their goalkeeper after winning the championship"
    
4. Gain weight, especially quickly or noticeably
   "He piled on the pounds during the holiday season"
    
5. (sports) join a tackle or scrum, often illegally after the whistle has blown
   "The referee penalized the defence for piling on after the play was over"

Derived forms: piled on, piles on, piling on

Encyclopedia: Pile on