Brat/bræt/ Definition 1 of 3Pro Tip 1/3Negative Connotation Brat often implies poor behavior and a lack of discipline; it can be insulting. The noisy brat disrupted the whole classroom. Pro Tip 2/3Usually Juvenile 'Brat' is most commonly used to describe children, not adults. That brat keeps throwing his food. Pro Tip 3/3Informal Use It's a casual word, more suitable for informal conversations and not formal situations. My cousin is such a brat sometimes.