Why do people use "mob" to refer to a single enemy?
1. A large disorderly crowd or throng. See Synonyms at crowd1.
2. The mass of common people; the populace.
3. Informal a. An organized gang of criminals; a crime syndicate.
b. often Mob Organized crime. Often used with the: a murder suspect with links to the Mob.
4. An indiscriminate or loosely associated group of persons or things: a mob of boats in the harbor.
5. Australian A flock or herd of animals.
tr.v. mobbed, mob·bing, mobs
1. To crowd around and jostle or annoy, especially in anger or excessive enthusiasm: Eager fans mobbed the popular singer.
2. To crowd into: Visitors mobbed the fairgrounds.
3. To attack in large numbers; overwhelm: The quarterback was mobbed by the defensive line.