c. 1610, "action of rising, upward movement," from ascend on model of descend/descent. The meaning "act of climbing" is from 1753.
Entries linking to ascent
ascend v.
late 14c., "move upward," from Latin ascendere "to climb up, mount," of planets, constellations, "come over the horizon," figuratively "to rise, reach," from ad "to" (see ad-) + scandere "to climb" (see scan (v.)). Also in 15c. used with a sense "to mount (a female) for copulation." The meaning "slope upward" is from 1832. Related: Ascended; ascending. An Old English word for it was stigan.