The Collaborative International Dictionary of English v.0.48:

Incorporative \In*cor"po*ra*tive\, a.
   Incorporating or tending to incorporate; as, the
   incorporative languages (as of the Basques, North American
   Indians, etc. ) which run a whole phrase into one word.
   [1913 Webster]

         History demonstrates that incorporative unions are
         solid and permanent; but that a federal union is weak.
                                                  --W. Belsham.
   [1913 Webster]

WordNet (r) 3.0 (2006):

incorporative
    adj 1: growing by taking over and incorporating adjacent
           territories; "the Russian Empire was a typical
           incorporative state"