From The Art and Popular Culture Encyclopedia
Terminal illness is medical terminology popularized in the 20th century for an active and malignant disease which cannot be cured and is expected to lead to death. Palliative care is often prescribed to manage symptoms and improve quality of life. A patient who has such an illness is referred to as a terminal patient or terminally ill.
Certain types of cancer, emphysema, liver failure, kidney failure, asbestosis, mesothelioma, some mental illness and heart disease may be considered fatal, although liver failure, kidney failure and even heart disease could possibly prolong life with an organ transplant. AIDS could be considered a terminal illness, but most patients with AIDS succumb to other illnesses due to their deficient immune systems.
A patient is considered to be terminally ill when he/ she has a medical prognosis of a life expectancy of six months or less. Though a patient may be considered terminal, it doesn't always guarantee that he/she will die.