The speaker suddenly launched into a fierce diatribe against government policies.

diatribe 来自希腊语 diatribē，原指"消磨时间"，后来演变为"长篇激烈的批评或谴责"。这个词通常指充满愤怒或敌意的长篇抨击性言论，特点是言辞激烈、情绪化。