The Collaborative International Dictionary of English v.0.48:

Subordination \Sub*or`di*na"tion\, n. [Cf. F. subordination.]
   1. The act of subordinating, placing in a lower order, or
      subjecting.
      [1913 Webster]

   2. The quality or state of being subordinate or inferior to
      an other; inferiority of rank or dignity; subjection.
      [1913 Webster]

            Natural creature having a local subordination.
                                                  --Holyday.
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   3. Place of inferior rank.
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            Persons who in their several subordinations would be
            obliged to follow the example of their superiors.
                                                  --Swift.
      [1913 Webster]

WordNet (r) 3.0 (2006):

subordination
    n 1: the state of being subordinate to something
    2: the semantic relation of being subordinate or belonging to a
       lower rank or class [syn: hyponymy, subordination]
    3: the grammatical relation of a modifying word or phrase to its
       head
    4: the quality of obedient submissiveness [ant:
       insubordination]
    5: the act of mastering or subordinating someone [syn:
       mastery, subordination]

Moby Thesaurus II by Grady Ward, 1.0:

43 Moby Thesaurus words for "subordination":
   assortment, back seat, categorization, continuity, culling, degree,
   gradation, grouping, hierarchy, humbleness, humility, inferiority,
   juniority, lower status, lowliness, minority, place, placement,
   rank, ranking, satellite status, screening, second fiddle,
   second string, secondariness, selection, sequence, serial order,
   service, servility, servitorship, sifting, sorting, sorting out,
   subjecthood, subjection, subordinacy, subordinate role,
   subservience, subserviency, taxonomy, third string, triage