‘层次’ (céng cì) literally combines ‘层’ (layer, stratum) and ‘次’ (order, sequence), together meaning a distinct level or tier within a structured system. It often implies hierarchy, progression, or gradation — whether physical (like geological strata or tree rings), conceptual (levels of understanding), or organizational (management tiers). Unlike simple counting words like ‘级’ (jí), ‘层次’ emphasizes qualitative distinction and relative position within a whole.

The term is common in academic, technical, and descriptive contexts — for example, discussing the complexity of language proficiency, ecological zones, or architectural design. It carries a neutral-to-formal register and rarely appears in casual speech unless referring to abstract sophistication (e.g., ‘思想的层次’ — depth of thinking). While ‘层’ alone can mean ‘floor’ (as in a building), adding ‘次’ shifts focus from mere quantity to ordered, meaningful differentiation.