To provide a working definition of professionalism for medical educators.Thus far, the literature has not provided a concise and inclusive definition of the word profession. There appears to be a need for one as a basis for teaching the cognitive aspects of the subject and for evaluating behaviors characteristic of professionals. Furthermore, a knowledge of the meaning of the word is important as it serves as the basis of the contract between medicine and society, and hence, of the obligations required of medicine to sustain the contract. A definition is proposed based on the Oxford English Dictionary and the literature on the subject. It is suggested that this can be useful to medical educators with responsibilities for teaching about the professions, professional responsibilities, and professional behavior.The proposed definition is as follows: Profession: An occupation whose core element is work based upon the mastery of a complex body of knowledge and skills. It is a vocation in which knowledge of some department of science or learning or the practice of an art founded upon it is used in the service of others. Its members are governed by codes of ethics and profess a commitment to competence, integrity and morality, altruism, and the promotion of the public good within their domain. These commitments form the basis of a social contract between a profession and society, which in return grants the profession a monopoly over the use of its knowledge base, the right to considerable autonomy in practice and the privilege of self-regulation. Professions and their members are accountable to those served and to society.