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fiduciary

noun, plural fi·du·ci·ar·ies.

Law. a person to whom property or power is entrusted for the benefit of another.

adjective

Law. of or relating to the relation between a fiduciary and his or her principal: a fiduciary capacity; a fiduciary duty.
of, based on, or in the nature of trust and confidence, as in public affairs: a fiduciary obligation of government employees.
depending on public confidence for value or currency, as fiat money.

noun plural -aries

a person bound to act for another’s benefit, as a trustee in relation to his beneficiary

adjective

1. having the nature of a trust
2. of or relating to a trust or trustee

adj.

1630s, from Latin fiduciarius “(holding) in trust,” from fiducia “trust” from root of fidere “to trust” (see faith). In Roman law, fiducia was “a right transferred in trust;” paper currency sense (1878) is because its value depends on the trust of the public. As a noun, from 1630s.