Source : Webster's Revised Unabridged Dictionary (1913)

Interdependence \In`ter*de*pend"ence\, n.
   Mutual dependence. ``The interdependence of virtue and
   knowledge.'' --M. Arnold.

Source : WordNet®

interdependence
     n : a reciprocal relation between interdependent entities
         (objects or individuals or groups) [syn: {mutuality}, {interdependency}]