‘夹层’ literally combines ‘夹’ (jiā), meaning ‘to sandwich’ or ‘to insert between’, and ‘层’ (céng), meaning ‘layer’ or ‘stratum’. Together, it refers to a thin layer situated between two other layers—like the filling in a sandwich or an intermediate structural level in architecture, geology, or materials science. It emphasizes position and spatial relationship rather than function or composition.

This term is commonly used in construction (e.g., a mezzanine floor), geology (e.g., sedimentary interlayers), food science (e.g., layered pastries), and even metaphorically in social or organizational contexts (e.g., an intermediary group). While ‘夹层’ sounds technical, it appears in everyday descriptions of buildings, packaging, or cooking—especially when distinguishing levels or hidden internal structures.