From Greek 'hierós' (sacred) + 'arkhein' (to rule) — originally ranked orders of angels and clergy, now any system of ranked authority.
A system in which members of an organization or society are ranked according to relative status or authority. A ranking of things according to importance or inclusiveness.
From Old French ierarchie, from Medieval Latin hierarchia, from Greek hierarkhia (ἱεραρχία, rule of a high priest, sacred governance), from hierarkhēs (ἱεράρχης, high priest), a compound of hieros (ἱερός, sacred, holy, divine) + arkhein (ἄρχειν, to rule, to lead, to be first). Greek hieros derives from PIE *ish₂-ro- (powerful, strong, sacred), a root also in Sanskrit iṣirá (vigorous, fresh). Greek arkhein, from PIE *h₂erḱ- (to begin, to rule), produces a vast family: archon (ruler), monarchy
The original hierarchy was not organizational but celestial. Pseudo-Dionysius the Areopagite, a mysterious sixth-century author, wrote 'The Celestial Hierarchy,' which ranked the nine orders of angels into three triads: Seraphim, Cherubim, and Thrones at the top; Dominations, Virtues, and Powers in the middle; Principalities, Archangels, and Angels at the bottom. This angelic org chart became enormously influential — Dante used it in the 'Paradiso,' Thomas Aquinas analyzed it in the 'Summa Theologica,' and