The Collaborative International Dictionary of English v.0.48:

Neighborliness \Neigh"bor*li*ness\, n.
   The quality or state of being neighborly.
   [1913 Webster]

WordNet (r) 3.0 (2006):

neighborliness
    n 1: a disposition to be friendly and helpful to neighbors [syn:
         neighborliness, neighbourliness, good-neighborliness,
         good-neighbourliness] [ant: unneighborliness]

Moby Thesaurus II by Grady Ward, 1.0:

30 Moby Thesaurus words for "neighborliness":
   amiability, amiableness, amicability, amicableness, amity,
   bonhomie, congeniality, cordiality, friendliness, friendship,
   generosity, geniality, graciousness, heartiness, hospitableness,
   hospitality, kindness, liberality, love, neighborlikeness,
   open door, openheartedness, peaceableness, receptiveness,
   sociability, unhostility, warmheartedness, warmness, warmth,
   well-affectedness