Our online medical glossary of medical terms and definitions includes definitions for terms related to treatment, and general medicine
ASCENDANT
1. Ascent; height; elevation. "Sciences that were then in their highest ascendant." (Temple)
2. 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.
Hence the phrases To be in the ascendant, to have commanding strength or influence, and Lord of the ascendant, one who has possession of such strength or influence; as, to rule, for a while, lord of the ascendant.
3. Superiority, or commanding influence; ascendency; as, one man has the ascendant over other. "Chievres had acquired over the mind of the youngmonarch 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.
Origin: F. Ascendant, L. Ascendens; p. Pr. Of ascendere.
Source: Websters Vocabulary