Source : Webster's Revised Unabridged Dictionary (1913)

Hierarchy \Hi"er*arch`y\, n.; pl. {Hierarchies}. [Gr. ?: cf. F.
   hi['e]rarchie.]
   1. Dominion or authority in sacred things.

   2. A body of officials disposed organically in ranks and
      orders each subordinate to the one above it; a body of
      ecclesiastical rulers.

   3. A form of government administered in the church by
      patriarchs, metropolitans, archbishops, bishops, and, in
      an inferior degree, by priests. --Shipley.

   4. A rank or order of holy beings.

            Standards and gonfalons . . . for distinction serve
            Of hierarchies, of orders, and degrees. --Milton.

Source : WordNet®

hierarchy
     n 1: a series of ordered groupings of people or things within a
          system; "put honesty first in her hierarchy of values"
     2: the organization of people at different ranks in an
        administrative body [syn: {power structure}, {pecking
        order}]

Source : Free On-Line Dictionary of Computing

hierarchy
     
        An organisation with few things, or one thing, at the top and
        with several things below each other thing.  An inverted tree
        structure.  Examples in computing include a directory
        hierarchy where each directory may contain files or other
        directories; a hierarchical {network} (see {hierarchical
        routing}), a {class hierarchy} in {object-oriented
        programming}.
     
        (1994-10-11)