A symptom is a departure from normal function or feeling which is noticed by a patient, indicating the presence of disease or abnormality. A symptom is subjective, observed by the patient, and cannot be measured directly. The term is sometimes also applied to physiological states outside the context of disease, as for example when referring to "symptoms of pregnancy".
A medical sign is an objective indication of some medical fact or characteristic that may be detected by a physician during a physical examination or by a clinical scientist by means of an in vivo examination of a patient. Signs may have no meaning to the patient, and may even go unnoticed, but may be meaningful and significant to the healthcare provider in assisting the diagnosis of medical condition(s) responsible for the patient's symptoms.