Source : Free On-Line Dictionary of Computing

concrete syntax
     
         The concrete syntax of a language including all the
        features visible in the source program such as {parentheses}
        and {delimiters}.  The concrete syntax is used when {parsing}
        the program or other input, during which it is usually
        converted into some kind of {abstract syntax tree}.
     
        Compare: {abstract syntax}.
     
        (1997-07-21)