Now Mary knew what happened at Jamaica Inn and it was very dangerous for her because her uncle was a violent man.

violent 是形容词，意思是"暴力的、凶暴的"，描述某人倾向于使用武力或表现出攻击性行为。这个词来自拉丁语 violentus，表示"猛烈的、激烈的"。