IPA: //ˈbræʃ.nəs//
KK: /bræʃnəs/
The quality of being bold, rude, or overly confident, often in a way that is disrespectful or unthoughtful.
His brashness often got him into trouble with his colleagues.
Brashness is formed from "brash" (originating from the Middle English "brash", meaning rash or impetuous) and "-ness" (a suffix indicating a state or quality). The word "brashness" refers to the quality of being rash or impetuous.
Think of someone who is acting rashly or impulsively — that's what brashness means, the state of being brash.