1. A quiet, painless death.
2. The deliberate ending of life in individuals with an incurable and painful disease.

Ethical considerations are still being actively debated. One difficulty is determining the criteria by which the physician, or society, determines that the time has come to end the patient's life.

The deliberate putting of someone to death because that person is suffering from a painful and incurable disease and desperately wants to die: Active euthanasia is another term for "mercy killing".

Euthanasia performed without the consent of a competent person.

Euthanasia provided to an incompetent person according to a surrogate's decision, or the decision of someone who is appointed to represent or act on behalf of another person.

Death resulting from the cessation of "heroic measures", or undertaking a procedure of therapy that is associated with an element of daring, or boldness, taken in an attempt to save a patient's life so as to prolong a life.

The term "heroic measure", refers to an aggressive, daring procedure in a dangerously ill patient that, in itself may endanger the patient but also has a possibility of being successful; whereas, a lesser degree of efforts would inevitably result in failure.