descendent

mid-15c. (adj.) "extending downward;" c. 1600 (n.) "an individual proceeding from an ancestor in any degree," from French descendant (13c.), present participle of descendre "to come down" (see descend).

Despite a tendency to use descendent for the adjective and descendant for the noun, descendant seems to be prevailing in all uses and appears 5 times more often than its rival in books printed since 1900. Compare dependant. In astrology, "the western horizon or cusp of the seventh house," 1680s.