1. The use, or tendency to use, obscene, vulgar, or profane language. Sometimes hyphenated. You might think that sort of trash-mouth is acceptable when you're with your friends, but you can stow it while you're under our roof, got it? My dad used to swear a blue streak all the time when I was a kid, so I developed a bit of a trash mouth as a result.
2. A person who uses such obscene, vulgar, or profane language. Sometimes hyphenated. He's actually a very intelligent guy, but he's such a trash mouth that he's hard to take seriously. We can't have a trash-mouth like that running our presentations.
3. The use, or tendency to use, disparaging, insulting, or abusive language. Sometimes hyphenated. The boxer is renowned for having quite a trash-mouth whenever he's face-to-face with his opponents before a match.
4. A person who uses such disparaging, insulting, or abusive language. Sometimes hyphenated. These politicians always turn into such trash mouths during their election campaigns.
n. someone who uses obscene language. Some “trash mouth” is making everybody mad over in the park.