He's in business with his cousin.
We decided to go into business together.
Our firm does a lot of business with overseas customers.
This new tax will put a lot of small companies out of business.
a business appointment/call/meeting
This week I have to go to Germany to do [some] business with one of our customers. (Skills for Life (Entry 2); A2; Spanish)
He runs a small IT business.
The two brothers set up/started up an office supplies business.
This is [a] horrible [time] to start a new job or business. (Preliminary English Test; B1; German)
I'm in Baltimore on business.
I was there on business. (Preliminary English Test; B1; Polish)
I'm certainly not going to tell Lara how much money I've spent - it's none of her business!
You might think it's none of my business, but I simply have to say this. (First Certificate in English; B2; Swedish)
I wish you'd just mind your own business.
Despite knowing that he was only doing what he thought was best for me, I couldn't stand him, and I often told him to mind his own business. (Certificate of Proficiency in English; C2; Portuguese)