—n. Law.a person to whom property or power is entrusted for the benefit of another.
—adj. 1. Law.of or pertaining to the relation between a fiduciary and his or her principal: a fiduciary capacity; a fiduciary duty. 2. of, based on, or in the nature of trust and confidence, as in public affairs: a fiduciary obligation of government employees. 3. depending on public confidence for value or currency, as fiat money.