niceness

from WordNet (r) 3.0 (2006)

niceness
    n 1: a courteous manner that respects accepted social usage
         [syn: {politeness}, {niceness}] [ant: {impoliteness}]
    2: the quality of nice [ant: {nastiness}]
    3: the quality of being difficult to detect or analyze; "you had
       to admire the subtlety of the distinctions he drew" [syn:
       {subtlety}, {niceness}]

from The Collaborative International Dictionary of English v.0.48

Niceness \Nice"ness\, n.
   Quality or state of being nice.
   [1913 Webster]