Source : Free On-Line Dictionary of Computing

qux
     
        /kwuhks/ The fourth of the standard {metasyntactic variable},
        after {baz} and before the quu(u...)x series.  See {foo},
        {bar}, {baz}, {quux}.  This appears to be a recent mutation
        from {quux}, and many versions (especially older versions) of
        the standard series just run {foo}, {bar}, {baz}, {quux}, ...