The word pool refers to many different things:

• A pool is a body of water. It is also called a pond. It can also mean a body of water that people have made. This is called a swimming pool.
• Pool is also a game. It is a form of billiards. The object is to use a cue ball to knock other balls into pockets around the edge of the table.
• People also use the word "pool" to mean something many people have contributed to. People can pool their money to buy something, or to make a bet. Sometimes it can mean cooperation, people working together to get something done.