In this paper, we discuss the largely neglected topic of semantics in medicine and the associated ethical issues. We analyse several key medical terms from the informed perspective of the healthcare professional, the lay perspective of the patient and the patient's family, and the descriptive perspective of what the term actually signifies objectively. The choice of a particular medical term may deliver different meanings when viewed from these differing perspectives. Consequently, several ethical issues may arise. Technical terms that are not commonly understood by lay people may be used by physicians, consciously or not, and may obscure the understanding of the situation by lay people. The choice of particular medical terms may be accidental use of jargon, an attempt to ease the communication of psychologically difficult information, or an attempt to justify a preferred course of action and/or to manipulate the decision-making process.