MSH: Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures.,NCI: Person under a physician's care for a particular disease or condition. NOTE: A subject in a clinical trial is not necessarily a patient, but a patient in a clinical trial is a subject. See also subject, trial subject, healthy volunteer. Often used interchangeably as a synonym for subject but healthy volunteers are not, strictly speaking, patients.,NCI: A patient is the subject of observations.,NCI: A person who receives medical attention, care, or treatment, or who is registered with medical professional or institution with the purpose to receive medical care when necessary.