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