Real Dictionary

mediate
verb: If someone mediates between two groups of people, or mediates an agreement between them, they try to settle an argument between them by talking to both groups and trying to find things that they can both agree to.
verb: If something mediates a particular process or event, it allows that process or event to happen and influences the way in which it happens.

mediate in American English
to be in an intermediate position or location
to settle by mediation
adjective: acting through, dependent on, or involving an intermediate agency; not direct or immediate
intransitive verb: to act between parties to effect an agreement, compromise, reconciliation, etc
transitive verb: to settle (disputes, strikes, etc.) as an intermediary between parties; reconcile

mediate in British English
adjective: occurring as a result of or dependent upon mediation
verb: to intervene (between parties or in a dispute) in order to bring about agreement