A cleric is a member of the clergy of a religion, especially one that has trained or ordained priests, preachers, or other religious professionals. Its non-specific nature means it is often used to refer to the religious leadership in Islam, where "priest" is not accurate and where terms such as "imam" are not widely understood.
The term "clerk" derives from "cleric", since in medieval times the clergy were one of the few groups who could read, and therefore were often employed to do bookkeeping and similar work. The term "clerical work" continues to this day to refer to such functions.