The Profanity Filter is enabled in Options Manager. In Discus 4.0 and higher, this can be found under the "Conv/Msg" tab when using the Options Manager in advanced mode.

Check the box next to "Profanity checker" and save the options to enable the profanity checker. To add words to the word list, click the "Edit Word List" link and type the bad words, one word per line, into the box. Please note that the "Edit Word List" function uses a pop-up window. This should work with most browsers, but if you click the link and nothing happens, check to make sure that you don't have a pop-up blocker or personal firewall blocking it.

The "bad word list" for your site is stored in the "cuss.txt" file in your Discus administration directory.