What is the meaning of POOL?

Is: 1. A group of people organized for a specific purpose or any communal combination of funds; 2. In capital budgeting, the concept that investment projects are financed out of a' POOL' of bonds, preferred stock, and common stock, and a weighted-average cost; 3. In insurance, a group of insurers who share premiums; and 4. In investments, the combination of funds for the benefit of a common project, or a group of investors who use their combined influence to manipulate prices.