trustee
US /ˌtrʌsˈtiː/
UK /ˌtrʌsˈtiː/

1.
an individual person or member of a board given control or powers of administration of property in trust with a legal obligation to administer it solely for the purposes specified.
:
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The university appointed a new trustee to oversee its endowment.
•
As a trustee, she is responsible for managing the family's assets.