'Dì jǐ lóu' literally means 'the which floor' and functions as an interrogative noun phrase meaning 'which floor?' in English. It combines the ordinal prefix 第 (dì), the interrogative numeral 几 (jǐ, meaning 'how many' or 'which' in counting contexts), and 楼 (lóu, meaning 'floor' or 'story' of a building). Unlike English, Chinese uses this fixed structure to ask about floor numbers — you cannot say *'jǐ lóu' alone in formal or standard questions for location; 'dì jǐ lóu' is the grammatically required form when seeking a specific floor number in a building.

This phrase is commonly used in daily interactions such as asking for directions in malls, apartments, or office buildings. It always appears in questions — never as a statement — and typically follows question words like 'nǎ lǐ' (where) or 'zài' (at), or appears directly as the subject/object of a question. Tone is important: 'jǐ' must carry the third tone, distinguishing it from 'jī' (first tone, meaning 'machine') or 'jì' (fourth tone, meaning 'to record').