[1] : The Collaborative International Dictionary of English v.0.48

ascendency \ascend"ency\, n.
   governing or controlling influence; the state that exists
   when one person or group has power over another; domination;
   power.
   1913 webster + wordnet 1.5

         an undisputed ascendency.                --macaulay.
   1913 webster

         custom has an ascendency over the understanding.
                                                  --watts.
   1913 webster

   syn: control; authority; influence; sway; dominion;
        prevalence; domination; dominance; ascendance;
        ascendence.
        1913 webster

[2] : WordNet (r) 2.0

ascendency
     n : the state that exists when one person or group has power
         over another; "her apparent dominance of her husband was
         really her attempt to make him pay attention to her"
         syn: dominance, ascendance, ascendence, ascendancy,
          control
see also:
dominance ascendance ascendence ascendancy control 

Ascendency >> A Words
Ascendency, definition of term: Ascendency
ascendency_pag1.html