The term symptom (from the Greeksyn = con/plus and pipto = fall, together meaning co-exist) has two similar meanings in the context of physical and mental health:
A symptom can be a physical condition which shows that one has a particular illness or disorder (see e.g. Longman, 1995). An example of a symptom in this sense of the word would be a rash.
Symptom - Glossary Entry - Genetics Home Reference
Some examples of symptoms are headache, fever, fatigue, nausea, vomiting, and pain.
Subjectiveevidence of disease or physical disturbance observed by the patientsymptom of many diseases>symptom of retinal arteriosclerosis>; broadly: something that indicates the presence of a physical disorder.
"The affair is a symptom of a global marital disturbance; it is not the disturbance itself"
Something visible or evident that gives grounds for believing in the existence or presence of something else: badge, evidence, index, indication, indicator, manifestation, mark, note, sign, signification, stamp, token, witness.