The Collaborative International Dictionary of English v.0.48:

Contemplativeness \Con*tem"pla*tive*ness\, n.
   The state of being contemplative; thoughtfulness.
   [1913 Webster]

WordNet (r) 3.0 (2006):

contemplativeness
    n 1: deep serious thoughtfulness [syn: pensiveness,
         meditativeness, contemplativeness]