祸患 is a formal, literary noun meaning 'disaster' or 'calamity'—an event causing great harm, suffering, or destruction. It combines two characters with overlapping negative meanings: 祸 (huò) means 'misfortune' or 'trouble', often implying moral or cosmic retribution, while 患 (huàn) means 'affliction', 'plague', or 'source of worry'. Together, they intensify the sense of grave, often large-scale adversity—not just minor mishaps but serious threats to safety, stability, or well-being.

The term appears frequently in classical texts, historical narratives, and modern formal writing (e.g., news reports on natural disasters or public health crises). It carries a weighty, somewhat solemn tone and is rarely used in casual speech. While it can refer to human-caused crises (e.g., war, corruption), it’s also commonly applied to natural calamities like floods, plagues, or invasive species outbreaks—hence its relevance to the 'Animals' topic, especially when discussing ecological threats such as pest infestations or disease-carrying wildlife.