ascent. n. 1. the act of ascending; climb or upward movement: the ascent of hot gases. 2. an upward slope; incline or gradient.3. movement back through time, as in tracing of earlier generations (esp in the phrase line of ascent).y means of ascent and descent consist simply in dilating or contracting the gas that is in the balloon by the application of different temperatures, and here is the method of obtaining that result.