coadjutor

n. assistant; one who works with another

A coadjutor bishop (or bishop coadjutor) is a bishop in the Roman Catholic or Anglican churches who is designated to assist the diocesan bishop in the administration of the diocese almost as co-bishop of the diocese. The coadjutor (literally, "co-assister" in Latin) is a bishop himself and is given authority even beyond that ordinarily given to the vicar-general (although a coadjutor is also appointed a vicar-general), making him co-ruler of the diocese in all but ceremonial precedence. In modern times, the coadjutor automatically succeeds the current bishop of a diocese upon the latter's retirement, removal or death.
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Noun
1. an assistant to a Bishop
(hypernym) assistant, helper, help, supporter

n. curate

n. coadjutor, assistant; one who works with another