[im.per.vi.ous] adj [L impervius, fr. in- + pervius pervious] (1650) 1 a: not allowing entrance or passage: impenetrable "a coat ~ to rain" b: not capable of being damaged or harmed "a carpet ~ to rough treatment"
2: not capable of being affected or disturbed "~ to criticism" -- im.per.vi.ous.ly adv -- im.per.vi.ous.ness n