Definition of: hierarchy

(hī′ər·är′kē) noun plural ·chies
1. A body of persons, especially ecclesiastics, ranked according to successive orders or classes.
2. Government or rule by a body of ecclesiastics organized in ranks or orders.
3. Theol. a Any of three ranks of angels. See ANGEL. b The body of angels collectively.
4. In science and logic, a series of systematic groups, as kingdoms, classes, orders, families, genera, and species. [<LL hierarchia <Gk. hierarchia rule of a hierarch]
—hi′er·ar′chic, hi′er·ar′chi·cal, hi′er·ar′chal adjective