Someone who manages property or other affairs for someone else WordNet 3.0 & Open English WordNet

A steward is an official who is appointed by the legal ruling monarch to represent them in a country and who may have a mandate to govern it in their name; in the latter case, it is synonymous with the position of regent, vicegerent, viceroy, king's lieutenant, governor, or deputy. Wikipedia

A representative of a monarch Wikipedia Disambiguation

Official who is appointed by the legal ruling monarch to represent them in a country Wikidata

A person who manages the property or affairs for another entity, particularly (historical) the chief administrator of a medieval manor. Wiktionary

Any administrator of the property or affairs of another. Wiktionary (translation)

The administrator of a medieval manor. Wiktionary (translation)