[ C ] usually disapproving a large, angry crowd, especially one that could easily become violent:

[ C ] informal a group of people who are friends or who are similar in some way:

[ S ] informal an organization of criminals:

[ T usually passive ] to come together around someone in a crowd to express admiration, interest, or anger:

[ I or T ] When birds or small animals mob a bigger or more frightening bird or animal that is hunting them, they attack it together and force it to go away.