ascendant

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 ]

☞ 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 ]