墨汁 (mò zhī) literally means 'ink juice' — 墨 (mò) refers to traditional Chinese ink, historically made from soot and animal glue, while 汁 (zhī) means 'juice' or 'liquid'. Together, they denote liquid ink used for calligraphy, painting, or writing with brushes. Though modern ink may be synthetic, the term retains its classical association with inksticks ground with water on an inkstone.

This word is commonly used in artistic, educational, and everyday contexts — for example, when buying supplies for Chinese language class or describing a messy spill during practice. It’s neutral in register and appears in both spoken and written Chinese. Unlike the more general term 墨 (mò), which can refer to solid inksticks or metaphorical 'ink' (e.g., in journalism), 墨汁 specifically emphasizes the liquid form ready for use.