hierarchy

Concise Oxford English Dictionary © 2008 Oxford University Press:
hierarchy /ˈhʌɪərɑːki/

▶noun (pl. hierarchies)

• 1 a ranking system ordered according to status or authority.

  ■ (the hierarchy) the upper echelons of a hierarchical system.

  ■ an arrangement according to relative importance or inclusiveness.

• 2 (the hierarchy) the clergy of the Catholic Church or of an episcopal Church.

• 3 Theology the traditional system of orders of angels and other heavenly beings.

– derivatives
hierarchization (or hierarchisation) noun,
hierarchize (or hierarchise) verb.

– origin ME: via OFr. and med. L. from Gk hierarkhia, from hierarkhēs (see hierarch).