Which word best describes someone who is rude, bad-tempered, or hostile?

The term "surly" is used to describe someone who is often rude, bad-tempered, or hostile. It conveys a sense of gruffness or unfriendliness in attitude and demeanor, aligning perfectly with the characteristics outlined in the question. When a person is labeled as surly, it indicates a tendency to be irritable, unapproachable, and generally unpleasant in interactions with others. This word captures the essence of negativity in social behavior, making it the most fitting choice among the options provided.

In contrast, "cheerful" denotes a positive and happy disposition, making it antithetical to the qualities described in the question. "Affable" refers to someone who is friendly and easy to talk to, which is also in stark contrast to the surly nature. "Compassionate" describes a person who is caring and empathetic, a trait that is fundamentally opposite to being rude or hostile. Therefore, "surly" not only fits the definition sought but encapsulates the precise tone indicating hostility and bad temper.