Combining its two Greek roots, syndrome means basically "running together". So when diagnosing a condition or disease, doctors tend to look for a group of symptoms existing together. As long as a set of symptoms remains mysterious, it may be referred to as a specific syndrome. But if that name is used for a while, it may become the condition's permanent name, even after an underlying cause has been found. So today we have Down syndrome, acquired immune deficiency syndrome, Asperger's syndrome, carpal tunnel syndrome, chronic fatigue syndrome, Tourette's syndrome, sick building syndrome, and many more. And since mental conditions often turn out to have physical causes, syndrome is used in psychology as well as in medicine.