hierarchyyoudaoicibaDictYouDict[hierarchy 词源字典]
hierarchy: [14] Greek hierós meant ‘sacred, holy’. Combined with -arkhēs ‘ruling’ (as in English archbishop) it produced hierárkhēs ‘chief priest’. A derivative of this, hierarkhíā, passed via medieval Latin hierarchia and Old French ierarchie into Middle English as ierarchie (the modern spelling was introduced on the basis of the Latin form in the 16th century).

At first the word was used in English for the medieval categorization of angels (into cherubs and seraphs, powers and dominions, etc), and it was not until the early 17th century that it was applied to the clergy and their grades and ranks. The metaphorical use for any graded system soon followed.
[hierarchy etymology, hierarchy origin, 英语词源]
hierarchy (n.)youdaoicibaDictYouDict
mid-14c., from Old French ierarchie, from Medieval Latin hierarchia "ranked division of angels" (in the system of Dionysius the Areopagite), from Greek hierarkhia "rule of a high priest," from hierarkhes "high priest, leader of sacred rites," from ta hiera "the sacred rites" (neuter plural of hieros "sacred;" see ire) + arkhein "to lead, rule" (see archon). Sense of "ranked organization of persons or things" first recorded 1610s, initially of clergy, sense probably influenced by higher. Related: Hierarchal; hierarchical.