‘衬衣’ (chèn yī) literally combines ‘衬’ (chèn), meaning ‘to line’, ‘to underlay’, or ‘to serve as an underlayer’, and ‘衣’ (yī), meaning ‘clothing’ or ‘garment’. Together, it refers to a lightweight, close-fitting upper-body garment worn next to the skin—most commonly an undershirt in mainland China and many other Mandarin-speaking regions. It’s typically made of cotton or synthetic fabric and serves both functional (absorbing sweat, protecting outer layers) and stylistic purposes.

In some regional contexts—especially in Taiwan and among older speakers—it may also refer to a formal ‘dress shirt’ (i.e., what English speakers call a ‘button-down shirt’). However, in standard mainland usage, ‘衬衫’ (chèn shān) is the preferred term for dress shirt, while ‘衬衣’ strongly implies an undershirt. The distinction matters in daily communication: using ‘衬衣’ to mean ‘dress shirt’ in Beijing may cause confusion or sound outdated.