The connotations of the term "a disease" were investigated by studying the ways in which both medical and non-medical people used the word. A list of common diagnostic terms was read slowly to groups of non-medical academic staff of a university, secondary-school students, medical academics, and family practitioners, who then indicated whether they thought each word referred to disease.All groups rated illnesses due to infections as diseases, but the doctors, and particularly the general practitioners, were more generous in accepting as diseases the terms for non-infectious conditions. Apart from the nature of the cause, the most influential factor in determining whether or not an illness was considered to be a disease was the importance of the doctor in diagnosis and treatment.These findings provide further evidence that there is ambiguity about the meaning of the term disease. To the layman a disease seems to be a living agency that causes illness. Doctors have obviously accepted more heterogeneous defining characteristics but remain reluctant to adopt unequivocally nominalist ways of thought. The position is not unlike that in the physical sciences, in which there is a good precedent for distinguishing between the formal scientific and the everyday uses of terms such as "force" and "power."
