Lewis & Short

ob-surdesco, dŭi, 3, v. inch. n., to become deaf (class.).

  1. I. Lit.: hoc sonitu oppletae aures hominum obsurduerunt, Cic. Rep. 6, 18, 19: si sapiens excaecatur, obsurdescat, etc., Aug. Civ. Dei, 19, 4, 4.
  2. II. Trop., to be deaf, not to give ear: obsurdescimus nescio quo modo, nec ea, quae ab eā (naturā) monemur, audimus, Cic. Lael. 24, 88: obsurduerunt aures hominum ad tam salutaria praecepta, Ambros. de Tobia, 3, 9.