Brutality is extreme cruelty, deliberate violent meanness. Avoid being the giver or receiver of brutality if you wish to remain a happy human.
Brutality comes from brutal (savage, fierce), plus -ity which makes it a noun. It’s the state of being a brute. Many criminals — especially murderers, rapists, and abusers — are guilty of brutality. Police brutality is what happens when the cops use extreme unnecessary force. Brutality is a strong word — just slapping someone isn't quite brutality. Brutality is more like beating a person with a tire iron. Brutality is also the name of a death metal band from Florida.