Attorney-in-fact

Origin

From attorney ("any personal representative") and fact ("act, deed"). Both words now rarely have those senses (outside of fixed expressions like this).

Full definition of attorney-in-fact

Noun

1. (US, legal) An agent of the person giving him/her the power of attorney (for a specific purpose or for general purposes) to act on his or her behalf. The attorney-in-fact’s power and responsibilities depend on the specific powers granted in the power of attorney document.