1. verb To speak negatively or unflatteringly about someone or something. Why are you always dirty-mouthing Tiffany? You don't even know her that well!

2. noun A person who uses obscenities, vulgarities, or profanities in their speech, especially at inappropriate times. Hey, you dirty-mouth! If I hear you speaking like that around your grandmother again, you're going to be grounded for a week! Well there's no need to be a dirty-mouth about it, Rick. You could have just said no like a civilized person.