Syndrome is one of the oldest terms in the medical vocabulary. Traditionally, the term has been used mainly as a designation for complex medical entities, such as multiple abnormalities, that are characterized by clusters of concurring symptoms, usually three or more. During the mid-twentieth century, the meaning and the use of the term were altered. First to take place was an attempt to eliminate physicians' names from syndrome nomenclature, resulting in a significant increase in the use of descriptive designations in proportion to eponyms. But the trend was counterbalanced by the creation of new classes of eponyms. Eponymous syndrome nomenclature now includes the names of literary characters, patients' surnames, subjects of famous paintings, famous persons, geographic locations, institutions, biblical figures, and mythological characters. This was followed by a relaxation in the scope of the definition of syndrome, wherein the term could also be used as a modifier indicating a special (sometimes unspecified) complexity of an already named pathological condition. Eventually syndrome changed from its original use as an exclusively medical term and came to mean anything unusual, abnormal, bizarre, or humorous, whether medical, social, behavioral, or cultural. This unrestrained use of the term is the principal cause of an enormous volume of the sometimes irrelevant syndrome literature cluttering databases in the MEDLARS system and of the deterioration of "SYNDROME" as a specific MeSH term and a useful search parameter.