Source : Free On-Line Dictionary of Computing

semantic network
     
         A {graph} consisting of {nodes} that represent physical
        or conceptual objects and arcs that describe the relationship
        between the nodes, resulting in something like a data flow
        diagram.  Semantic nets are an effective way to represent data
        as they incorporate the inheritance mechanism that prevents
        duplication of data.  That is, the meaning of a concept comes
        from its relationship to other concepts and the information is
        stored by interconnecting nodes with labelled arcs.
     
        (1999-01-07)