Webster’s Revised Unabridged Dictionary · 1913
Interjacence
In′ter·ja′cence, 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.
England and Scotland is divided only by the interjacency of the Tweed. Sir M. Hale.