1. (
financial) The purchase of a company's
shares by the
management. If money is borrowed to do this (as often happens), it is called a
leveraged buyout.
2. (financial) The purchase of a company's shares by the company, thus removing itself from the stock market.
3. (business) The purchase of an Intellectual Property, where you are allowed to use the IP in any way you want (without royalties or restrictions on what projects you can use it for).