A custodian who is hired to take care of something (property or a person).

Roget 758: consignee, trustee, nominee, committee.    agent, delegate; commissary, commissioner; emissary, envoy, commissionaire [Fr.]; messenger etc. 534.    diplomatist, diplomat, diplomate, corps diplomatique [Fr.], embassy; ambassador, embassador^†; representative, resident, consul, legate, nuncio, internuncio^†, charge d'affaires [Fr.], attache.    vicegerent etc. (deputy) 759; plenipotentiary.    functionary, placeman^†, curator; treasurer etc. 801; factor, bailiff, clerk, secretary, attorney, advocate, solicitor, proctor, broker, underwriter, commission agent, auctioneer, one's man of business; factotum etc. (director) 694; caretaker; dalal^†, dubash^†, garnishee, gomashta^†.    negotiator, go-between; middleman; under agent, employe; servant etc. 746; referee, arbitrator etc. (judge) 967.    traveler, bagman, commis-voyageur [Fr.], touter^†, commercial traveler, drummer [U.S.], traveling man.    newspaper correspondent, own correspondent, special correspondent.    ... show more

Dutch: tutor, voogd, oppasser, opziener, toezichthouder
Polish: dozorca

An official who performs the duties of an office temporarily.

Polish: p.o., pełniący obowiązki