Lewis & Short

2. dēscensus, ūs, m. [descendo], a descent (rare; not in Cic. and Caes.).

  1. I. In gen.: qua illi descensus erat, Sall. C. 57, 3.
    1. B. Concr., a descending way, a descent: difficilis et praeruptus, Hirt. B. G. 8, 40, 4 and 5; cf.: facilis descensus Averno, Verg. A. 6, 126: ipso descensu Jovis speluncae, Plin. 16, 26, 46, § 110: montis, Vulg. Luc. 19, 37.
  2. * II. In partic. (acc. to descendo, no. I. B. 5), obscene, a lying down, Varr. R. R. 2, 5, 13.