There are two lists of offensive curse words which the filter acts on: filter words and drop words. These are highlighted in yellow and red in the chat window respectively. A player can determine how filter words are filtered, but drop words always cause an entire message to be unsendable.
Additionally, some non-offensive words, if typed, will always be substituted for more piratey variants independent of a pirate's filtering choice. These are known as substitutions.
There are four choices of filter in the game to weed out filter words, found on the "Ye->Options->Chat" screen. Pirates have the option to "pirate-ify" or "comic-ify" the curse words, they may "Drop chat messages with curse words", or they may leave their chat "Unfiltered". Both incoming and outgoing messages are filtered. Note that both pirate-ifying and comic-ifying replace the curse words permanently, thus incoming words in this form will remain in this form.
With this filter choice, certain potentially offensive text strings are each replaced with a more mild piratey equivalent.
This filter choice will randomly replace each letter of a curse word with one of the following characters: !%@#$&* . Note that the comic-ified curse word is the same length as the original word, so this filtering option may still cause offense if used.
Dropping messages with offensive content
This filter option means that a message containing a curse word cannot be sent. Further, any messages containing curse words that are received through any chat channel will be deleted before they can be displayed.
Incoming and outgoing messages are not monitored for curse words.