Dictionary.net

A power of attorney that remains in effect if the principal becomes incapacitated. If a power of attorney is not specifically made durable, it automatically expires if the principal becomes incapacitated. See durable power of attorney for finances; durable power of attorney for healthcare.

Declarations by patients, made in advance of a situation in which they may be incompetent to decide about their own care, stating their treatment preferences or authorizing a third party to make decisions for them. (Bioethics Thesaurus)