From GNU Collaborative International Dictionary of English, version 0.54:
Mediation (?), n. [OE. mediacioun, F. médiation. See {Mediate}, a.]
1. The act of mediating; action or relation of anything interposed; action as a necessary condition, means, or instrument; interposition; intervention.
[1913 Webster]
The soul [acts] by the mediation of these passions.
-- South.
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2. Hence, specifically, agency between parties at variance, with a view to reconcile them; entreaty for another; intercession.
Bacon.
[1913 Webster]