汉沽区 is formed from three characters: 汉 (Hàn), which in this context primarily references the Han River or the Han ethnicity, 沽 (gū), meaning a river estuary or waterfront area, and 区 (qū), meaning district. The combination 汉沽 specifies a geographical location near the Han River estuary, and the addition of 区 categorizes it as an administrative division.