A 
syndrome is a set of 
medical signs and 
symptoms that are 
correlated with each other and, often, with a particular 
disease or disorder.
[1] The word derives from the 
Greek σύνδρομον, meaning "concurrence".
[2] In some instances, a syndrome is so closely linked with a 
pathogenesis or cause that 
the words syndrome, disease, and disorder end up being used interchangeably for them. This is especially true of 
inherited syndromes. For example, 
Down syndrome, 
Wolf–Hirschhorn syndrome, and 
Andersen syndrome are disorders with known pathogeneses, so each is more than just a set of signs and symptoms, despite the syndrome nomenclature. In other instances, a syndrome is not specific to only one disease. For example, 
toxic shock syndromecan be caused by various toxins; premotor syndrome can be caused by various brain lesions; and 
premenstrual syndrome is not a disease but simply a set of symptoms.