INTERRELATION

from WordNet (r) 3.0 (2006)

interrelation
    n 1: mutual or reciprocal relation or relatedness;
         "interrelationships of animal structure and function" [syn:
         {interrelation}, {interrelationship}, {interrelatedness}]

from The Collaborative International Dictionary of English v.0.48

Interrelation \In`ter*re*la"tion\, n.
   Mutual or reciprocal relation; correlation.
   [1913 Webster]

from Bouvier's Law Dictionary, Revised 6th Ed (1856)

INTERRELATION, civil law. The act by which, in consequence of an agreement, 
the party bound declares that he will not be bound beyond a certain time. 
Wolff, Inst. Nat. Sec. 752. 
     2. In the case of a lease from year to year, or to continue as long as 
both parties please, a notice given by one of them to the other of a 
determination to put an end to the contract, would bear the name of 
interrelation.