Pond
Within marketing and sales, a pond refers to the entire target group of potential customers that a company must rely on when acquiring new customers. The smaller the pond, the more targeted marketing efforts must be to reach and convince enough potential customers to achieve the desired sales and growth.
The metaphor of a pond filled with potential customers is also found in the expressions "fishing in the same pond." This means that two companies are in direct competition by trying to sell similar products or services to the same target market.