Which category of sins does profanity lie under-mortal sins, or venial sins?
Vulgarity is venial because it’s merely crass and not the kind of thing that ought to be said by Christians. But swearing is different if it calls on God to damn others and that kind of thing. The intention is what is important as to its being mortal or venial sin. If in doubt always ask your confessor for clarification.
Depends on the utterer, the nature of the profanity/curse, personal knowledge, purpose and context - IMHO it can come under either category.
Best to avoid the occasion of sin and not profane/curse.
Vulgarity is a lazy mind expressing itself. Taking the Lord’s name in vain with full consent could be a mortal sin but all else is pretty much showing others the lack of command that one has on his or her language.
Can depend on what one means. (like is one using just the s word --what is being said etc etc is grave harm being inflicted etc)
Often various “bad words” is “venial” but still of course to be avoided. Some can be said I think to be “not sinful”.
Regarding a misuse of the name of the Lord – one can distinguish between blasphemy (and other grave offenses) and profanity /disrespectful use of the Holy name in anger say at the hammer that smashed your thumb etc that is not blasphemy --not said out of contempt for God or directed at God… that such in itself --while certainly NOT to be done (we are Christians --we love and reverence the Holy Name of Jesus etc-and as St. Paul says --let no evil talk come from your mouths) - is ordinarily venial.
Again such ought to be removed…
Let us praise and bless the Holy Name!
Praised be Jesus Christ of Nazareth --now and forever!
(If say one is in a habit of misuse of the Divine name and is working at avoiding such as one ought --particularly great effort/care ought to be taken around children…).
Your confessor can assist you in particulars (though I would suggest one take care how one asks in confession…abbreviate etc.)