Medical education is expensive. There is a growing interest in the subject of cost and value in medical education. However, in the medical education literature, terms are sometimes used loosely - and so there is a need for basic grounding in the meaning of commonly used and important terms in medical education economics. The purpose of this article is to define some terms that are frequently used in economic analysis in medical education. In this article, terms are described, and the descriptions are followed by a worked example of how the terms might be used in practice. The following terms are described: opportunity cost, total cost of ownership, sensitivity analysis, viewpoint, activity-based costing, efficiency, technical efficiency, allocative efficiency, price and transaction costs.