to be in the ascendant

Webster's Dictionary (GCIDE)

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

1.Ascent; height; elevation. [R.] [1913 Webster]

Sciences that were then in their highest ascendant.— Temple.[1913 Webster]

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. [1913 Webster]

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. [1913 Webster]

3.Superiority, or commanding influence; ascendency; as, one man has the ascendant over another. [1913 Webster]

Chievres had acquired over the mind of the young monarch the ascendant not only of a tutor, but of a parent.— Robertson.[1913 Webster]

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. [1913 Webster] Ascendant