The Collaborative International Dictionary of English v.0.48:

Coadunation \Co*ad`u*na"tion\, n. [L. coadunatio.]
   Union, as in one body or mass; unity. --Jer. Taylor.
   [1913 Webster]

         The coadunation of all the civilized provinces.
                                                  --Coleridge.
   [1913 Webster]