It is Greek for Elder. It was transliterated into Latin and English for use referring to a church official. It is usually used for the highest ranking clergy in a local church. In some churches it is also used for the highest ranking laymen.
It originates from prehistoric Germanic "andswaru", having been a compound form in Old English from "and" ( = against ) + "swerian" ( = swear ); thus a kind of counter-question said in time as a...