[ upper dup lower != ] is letter    ( c --> b )

               forward is backwords ( $ --> $ )

[ [ behead
    dup letter while
    emit again ]
  dup emit
  char . !=
  if backwords ]       is forwords  ( $ --> $ )

[ [ behead
    dup letter while
    swap recurse
    rot emit ]
  dup emit
  char . !=
  if forwords ]  resolves backwords ( $ --> $ )

[ forwords drop cr ]   is oddwords  ( $ -->   )

$ "we,are;not,in,kansas;any,more." oddwords
$ "what,is,the;meaning,of:life."   oddwords