The collective name for five major freshwater lakes in China, most commonly referring to 洞庭湖 dòng​tíng​hú, 鄱阳湖 pó​yáng​hú, 太湖 tài​hú, 巢湖 cháo​hú, and 洪泽湖 hóng​zé​hú

the four borders of ancient China; (by extension) the whole world; the entire country