What term is used for a collection of symptoms that characterize a particular disease?

The correct term for a collection of symptoms that characterize a particular disease is "Syndrome." This term is used in medical and clinical contexts to describe a group of signs and symptoms that occur together and are indicative of a specific health condition. For example, the term "Down syndrome" refers to a set of physical and developmental characteristics associated with a chromosomal condition.

The other choices refer to different concepts in the medical field. "Condition" is a more general term that may describe any disease or state of health but does not specifically imply a collection of symptoms. "Diagnosis" refers to the identification of a disease or condition based on the symptoms and signs presented, while "Illness" describes the experience of symptoms by an individual and their perception of their health status, which may not necessarily correspond to a specific collection of symptoms.