Source : Free On-Line Dictionary of Computing

Moore graph
     
        A {graph} which achieves the {Moore bound}.  These are
        {complete graph}s, {polygon graph}s ({regular graph}s of
        {degree} 2) and three others: (nodes, degree, diameter) =
        (10,3,2), (50,7,2) and the possible but undiscovered
        (3250,57,2).