Lewis & Short

dē-crĕpĭtus, a, um, adj. [crepo] (lit., noiseless; applied to old people, who creep about like shadows), very old, decrepit (mostly ante-class.): vetulus, decrepitus senex, Plaut. Merc. 2, 2, 43; so, senex, id. ib. 20; id. Asin. 5, 2, 13; Ter. Ad. 5, 8, 16: senex, Vulg. 2 Par. 36, 17: leo, Prud. Ham. 561: inter decrepitos me numera et extrema languentes, Sen. Ep. 26: aetas (bestiolae), * Cic. Tusc. 1, 39 fin.