na-adjective, noun
Describes a person or behavior that is rude, arrogant, and domineering. A literary or formal word; in casual speech, 横柄 or 傲慢 are more common.
彼の暴慢な態度に周囲は辟易した。
Everyone was fed up with his overbearing attitude.
Compound of 暴 (violent, rude) and 慢 (arrogant, lazy). The exact historical derivation is uncertain, but the meaning follows from the kanji components.