De*scen"sion (?), n. [OF. descension, L. descensio. See Descent.]
The act of going downward; descent; falling or sinking; declension; degradation.
Oblique descension Astron., the degree or arc of the equator which descends, with a celestial object, below the horizon of an oblique sphere. -- Right descension, the degree or arc of the equator which descends below the horizon of a right sphere at the same time with the object. [Obs.]
© Webster 1913.