Q. 77: What is forbidden in the seventh commandment?
A. The seventh commandment forbids all unchaste thoughts, words, and actions.
But fornication and all uncleanness or covetousness, let it not even be named among you, as is fitting for saints; neither filthiness, nor foolish talking, nor coarse jesting, which are not fitting, but rather giving of thanks. Ephesians 5:3-4