interjacency

from The Collaborative International Dictionary of English v.0.48

Interjacence \In`ter*ja"cence\, Interjacency \In`ter*ja"cen*cy\,
   n. [See {Interjacent}.]
   The state of being between; a coming or lying between or
   among; intervention; also, that which lies between.
   [1913 Webster]

         England and Scotland is divided only by the
         interjacency of the Tweed.               --Sir M. Hale.
   [1913 Webster]