Source : Webster's Revised Unabridged Dictionary (1913)

Ascendant \As*cend"ant\, n. [F. ascendant, L. ascendens; p. pr.
   of ascendere.]
   1. Ascent; height; elevation. [R.]

            Sciences that were then in their highest ascendant.
                                                  --Temple.

   2. (Astrol.) The horoscope, or that degree of the ecliptic
      which rises above the horizon at the moment of one's
      birth; supposed to have a commanding influence on a
      person's life and fortune.

   Note: Hence the phrases

   {To be in the ascendant}, to have commanding power or
      influence, and

   {Lord of the ascendant}, one who has possession of such power
      or influence; as, to rule, for a while, lord of the
      ascendant. --Burke.

   3. Superiority, or commanding influence; ascendency; as, one
      man has the ascendant over another.

            Chievres had acquired over the mind of the young
            monarch the ascendant not only of a tutor, but of a
            parent.                               --Robertson.

   4. An ancestor, or one who precedes in genealogy or degrees
      of kindred; a relative in the ascending line; a
      progenitor; -- opposed to {descendant}. --Ayliffe.