a pattern of symptoms indicative of some disease
"After weeks of fatigue, joint pain, and fever, the doctor finally diagnosed him with lupus syndrome based on that distinct cluster of symptoms."
A recognizable pattern of signs, symptoms and/or behaviours, especially of a disease or medical or psychological condition.
"After extensive testing confirmed the cluster of fatigue, joint pain, and memory loss, the doctor finally diagnosed her with chronic fatigue syndrome."
In plain English: A syndrome is a group of symptoms that happen together and usually point to a specific health problem.
"Many doctors believe that stress and poor diet can lead to an unhealthy syndrome known as metabolic syndrome."
Usage: Use syndrome to describe a specific cluster of physical or behavioral symptoms that occur together as part of an illness or disorder. Avoid using it for isolated incidents unless they are consistently linked by experts into a recognized pattern.
The word syndrome entered English from New Latin in the 19th century. It originally described a concurrence of symptoms, derived from Ancient Greek roots meaning "running together."