Cruelty is a characteristic of deliberately causing someone pain. Years of cruelty by their leaders can cause citizens to rise up together and revolt.
Keeping a dog tied up outside all day and all night is animal cruelty, while kids' endless bullying of a classmate is another kind of cruelty. In both examples, people act in a coldhearted way that causes another being to feel terrible. The Latin root of cruelty is crudelis, "rude, unfeeling, or hard-hearted," which is related to crudus, "rough, raw, or bloody," the root of crude.