1. an abnormally large head
2. someone who regard highly of themselves; cocky
3. someone who is lazy; an arse
4. a selfish person
5. someone who copies work off others and make it their own.
1. He thinks he is smart because he has a mack.
2. You are just as equal as everyone else, so don't be such a mack.
3. Get off your mack and start working.
4. You're a tight-arse mack.
5. That bastard macked my works.