The Collaborative International Dictionary of English v.0.48:

Halfness \Half"ness\ (h[aum]f"n[e^]s), n.
   The quality of being half; incompleteness. [R.]
   [1913 Webster]

         As soon as there is any departure from simplicity, and
         attempt at halfness, or good for me that is not good
         for him, my neighbor feels the wrong.    --Emerson.
   [1913 Webster]