As used in sections 459.010 to 459.055, the following terms mean:
(1) "Attending physician", the physician selected by, or assigned to, the patient who has primary responsibility for the treatment and care of the patient;
(2) "Competent person", a person eighteen years of age or older of sound mind who is able to receive and evaluate information and to communicate a decision;
(3) "Death-prolonging procedure", any medical procedure or intervention which, when applied to a patient, would serve only to prolong artificially the dying process and where, in the judgment of the attending physician pursuant to usual and customary medical standards, death will occur within a short time whether or not such procedure or intervention is utilized. Death-prolonging procedure shall not include the administration of medication or the performance of medical procedure deemed necessary to provide comfort, care or to alleviate pain nor the performance of any procedure to provide nutrition or hydration;
(4) "Declaration", a document executed in accordance with the requirements of section 459.015;
(5) "Physician", a person licensed to practice medicine and surgery by the state board of registration for the healing arts;
(6) "Terminal condition", an incurable or irreversible condition which, in the opinion of the attending physician, is such that death will occur within a short time regardless of the application of medical procedures.