What is a software cost estimate? Is it the most likely cost, the planned cost, the budget, the price, or, something else? Through comparison with vacation cost estimation and a real-life case we illustrate that it is not meaningful to compare and analyze cost estimates unless it is clear which interpretation is applied. Unfortunately, the software industry, software engineering textbooks and scientific estimation studies do frequently not clarify how they apply the term {`}cost estimate'. We argue that this lack of clarity may lead to conflicting estimation goals, communication problems, and, learning problems, and provide recommendations on how to deal with these problems.