The Collaborative International Dictionary of English v.0.48:

Interrelated \In`ter*re*lat"ed\, a.
   Having a mutual or reciprocal relation or parallelism;
   correlative.
   [1913 Webster]

WordNet (r) 3.0 (2006):

interrelated
    adj 1: reciprocally connected [syn: interconnected,
           interrelated]

Moby Thesaurus II by Grady Ward, 1.0:

35 Moby Thesaurus words for "interrelated":
   affiliate, affiliated, allied, associate, associated, bound,
   bracketed, collateral, conjugate, connected, correlated, coupled,
   implicated, interaffiliated, interallied, interconnected,
   intercoupled, interdependent, interlinked, interlocked, intertied,
   involved, joined, knotted, linked, of that ilk, of that kind,
   parallel, related, spliced, tied, twinned, wed, wedded, yoked