These words refer to evidence from which a whole situation, such as the presence of a disease, may be inferred. Symptom relates closely to a medical context, applying to any manifestations of unusual functioning that may or may not be relevant to a diagnosis: unexplained symptoms of dizziness and nausea. Similarly, each abnormal condition or disease exhibits characteristic symptoms : required to name the tell-tale symptoms of hundreds of diseases. A syndrome is that set of symptoms that always occur together and are characteristic of a particular disease, whether physical or mental. A syndrome is not the sum total of random symptoms detected in someone at a given check-up, but only those that fit together into the typical picture of a specific disease or ailment: the syndrome for one kind of hepatitis that includes yellowing of the skin, extreme fatigue and certain digestive disorders; delusions, the hearing of voices, and a feeling of being persecuted that are an inevitable part of the paranoid’s syndrome . This word has become a fad word for any set of characteristics commonly fund in association, usually used with a negative tone: recognizing in him the whole Marxist syndrome after the briefest of conversations. Prodrome , a medical term, does not, like syndrome , refer to a collection of symptoms but to any single symptom that is premonitory of an approaching disease: the chronic aneamia that may be a prodrome for leukaemia.

While indication and clue may be used in a medical context, both are also used widely outside it. Clue , in fact, relates more directly to the field of criminology than to medicine. As such, it refers to the evidence by which a crime may be solved or from which a whole situation may be inferred: gathering clues at the scene of the murder that could lead them to the killer. In a wider context, the word can refer to any tell-tale evidence whether given intentionally or inadvertently: asking for some clue as to how she felt about him; noticing several clues that suggested he had interests similar to her own. Indication is the most general of these words and can point to any piece of tell-tale evidence in any situation or context: indications of the drug’s effectiveness; indications that a quarrel had immediately preceded the murder; giving her innumerable indications of a country’s economic health.