na-adjective, noun
Describes violent, cruel, or wildly aggressive behavior, often of people, animals, or acts. Can also modify abstract nouns like 性格 or 事件.
その犬は凶暴で、近づくのは危険だ。
That dog is ferocious; it's dangerous to go near it.
彼は凶暴な性格で、すぐに暴力を振
He has a brutal nature and quickly resorts to violence.
Compound of 凶 (bad, evil, disaster) and 暴 (violent, outburst). The spelling 兇暴 uses the older form 兇, which carries a similar meaning of 'wicked' or 'ominous', but is now rare.