WordNet (r) 3.0 (2006):

piousness
    n 1: righteousness by virtue of being pious [syn: piety,
         piousness] [ant: impiety, impiousness]

Moby Thesaurus II by Grady Ward, 1.0:

45 Moby Thesaurus words for "piousness":
   Tartuffery, Tartuffism, adoration, affectation, cant, churchgoing,
   conformity, cultism, devotedness, devotion, devoutness,
   dutifulness, faith, faithfulness, false piety, falseness,
   goody-goodiness, hypocrisy, insincerity, love of God,
   mealymouthedness, mummery, observance, oiliness, pharisaicalness,
   pharisaism, pietism, pietisticalness, piety, religion, religionism,
   religiosity, religiousness, reverence, sanctimoniousness,
   sanctimony, self-righteousness, snivel, snuffle, theism, unction,
   unctuousness, veneration, worship, worshipfulness