The Collaborative International Dictionary of English v.0.48:

Associability \As*so`cia*bil"i*ty\, n.
   The quality of being associable, or capable of association;
   associableness. "The associability of feelings." --H.
   Spencer.
   [1913 Webster]

WordNet (r) 3.0 (2006):

associability
    n 1: the capability of being easily associated or joined or
         connected in thought [syn: associability,
         associableness]