Source : Webster's Revised Unabridged Dictionary (1913)

Unicity \U*nic"i*ty\, n. [L. unicus single. See {Unique}.]
   The condition of being united; quality of the unique;
   unification.

         Not unity, but what the schoolmen call unicity. --De
                                                  Quincey.

         The unicity we strive not to express, for that is
         impossible, but to designate by the nearest analogy.
                                                  --Coleridge.