盛怒 is a formal noun meaning 'great anger' or 'wrath' — a state of intense, often visible fury. It's more literary and intense than 生气 or 愤怒, and you'll typically find it in written narratives, news reports, or historical texts rather than everyday conversation. It often appears in phrases like 盛怒之下 ('in a fit of rage') to describe actions taken while in that state.