The Collaborative International Dictionary of English v.0.48:

neighbour \neighbour\, neighbouring \neighbouring\,
neighbourhood \neighbourhood\, neighbourly \neighbourly\
   Same as neighbor, neighboring, neighborhood,
   neighborly. [Chiefly Brit.]
   [PJC]

WordNet (r) 3.0 (2006):

neighbourly
    adj 1: exhibiting the qualities expected in a friendly neighbor
           [syn: neighborly, neighbourly]