Uncaught ReferenceError: jQuery is not defined

適当なクエリを先に読み込むことで解決出来る

    <script src="//ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
    <script src="./js/jquery.xdomainajax.js"> </script>
    <script> var wp_url_admin_ajax = 'http://192.168.33.10/wp-admin/admin-ajax.php'; </script>
    <script>
      jQuery(function ($) {
        $.ajax({
          type: 'POST',
          url: wp_url_admin_ajax,
          data: {
            'action': 'tell_me'
          },
          success: function (response) {
            console.log(response);
            json = eval("(" + response + ")");
            if (json.err) {
              result = "error:404";
            } else {
              console.log(json);
            }
          }
        });
      });
    </script>