The advance of medical semantics is, in general, towards causation. As knowledge increases, the common consequence is the re-definition of disease. This starts with symptoms then a disorder of structure or function, abnormalities of images, genetics or biochemistry, the ultimate aim being a specific aetiological mechanism which replaces broader descriptions. But medical terminology of diseases, diagnoses and syndromes is inherently imprecise. Careless nomenclature causes confused dialogue and communication. Symptoms of uncertain cause are commonly lumped together and given a new 'diagnostic' label which also may confuse and produce false concepts that stultify further thought and research. Such medicalisation of non-specific aggregations of symptoms should be avoided. The defining characteristics of diseases and diagnoses should be validated and agreed. The pragmatic diagnoses of 'symptom of unknown cause' or 'non-disease' are preferable to falsely labelling patients with obscure or non-existent diseases. "I tried to unveil the stillness of existence through a counteracting murmur of words, and, above all, I confused things with their names: that is belief." Jean-Paul Sartre (The Words, 1964).