The Collaborative International Dictionary of English v.0.48:
Inconsiderateness \In`con*sid"er*ate*ness\, n. The quality or state of being inconsiderate. --Tillotson. [1913 Webster]WordNet (r) 3.0 (2006):
inconsiderateness n 1: the quality of failing to be considerate of others [syn: inconsideration, inconsiderateness, thoughtlessness] [ant: considerateness, consideration, thoughtfulness]