Synonyms for Mediate (same or very similar meaning)
WordNet sense 1 (being neither at the beginning nor at the end in a series):
in-between, middle
WordNet sense 2 (lying between two extremes in time or space or degree):
intermediate, intermediate
WordNet sense 3 (having intervening factors or persons or influences):
indirect
WordNet sense 4 (act between parties with a view to reconciling differences):
arbitrate, intercede, liaise
From the ODE community, based on WordNet
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