Other forms: brasher; brashest
Brash sounds like what it means: harsh, loud, and maybe a little rude. Sometimes that’s good, like when you have a serious rash on your face and give Aunt Nell a brash warning before she showers you with kisses.
There's nothing warm and fuzzy about brash. New Yorkers are sometimes thought of as the poster children for brash behavior: they can be bold and brazen. Pushy even. You might find brashness offensive, or maybe you think it's refreshingly direct. If you're a cab driver, a tough exterior might be useful, but being brash probably won’t advance your career if you work in a hotel, where you’re supposed to be polite and welcoming.