Source : Free On-Line Dictionary of Computing

Media Access Unit
     
         (MAU or Multistation Access Unit, MSAU) In a
        {Token Ring} network, a device to attach multiple network
        stations in a star topology, internally wired to connect the
        stations into a logical ring.  The MAU contains relays to
        short out nonoperating stations.  Multiple MAUs can be
        connected into a larger ring through their Ring In/Ring Out
        connectors.
     
        (1997-05-27)