2) taking a piss
3) art of screwing people for profit
4) selling air, such as trading in stock market
5) pointless meaningless life-consuming spirit-draining activity
2) i'm going to do some business behind that bush
3) these corporations merged and small-time enterprisers went out of business.
4) Jackie won 4 millions by selling stock just before it crashed while a few unlucky lost their life-time savings by buying it. That's business, kid. (see also gambling)
5) I'm a corporate dumbass. I work my ass off 16 hours a day, I have a luxury car, deluxe mansion, posh furniture but i have no time to enjoy my life.