NEUROTIC concern for one's health. Refers to excessive preoccupation or worry about having a serious illness. An individual suffering from hypochondriasis is known as a hypochondriac. Often, hypochondria persists even after a physician has evaluated a person and reassured them that their concerns about symptoms do not have an underlying medical basis or, if there is a medical illness, the concerns are far in excess of what is appropriate for the level of disease. Many hypochondriacs focus on a particular symptom as the catalyst of their worrying, such as gastro-intestinal problems, palpitations, or muscle fatigue.