unicity

CIDE DICTIONARY

unicity, n. [L. unicus single. See Unique.].

The condition of being united; quality of the unique; unification. [1913 Webster]

"Not unity, but what the schoolmen call unicity." [1913 Webster]

"The unicity we strive not to express, for that is impossible, but to designate by the nearest analogy." [1913 Webster]

For further exploring for "unicity" in Webster Dictionary Online