座垫 (zuò diàn) literally combines 座 (zuò), meaning 'seat' or 'place to sit', and 垫 (diàn), meaning 'cushion' or 'pad'. Together, they refer specifically to a removable cushion placed on a chair, bench, car seat, or bicycle saddle to improve comfort, support, or aesthetics. Unlike built-in padding, a 座垫 is typically detachable and may be made of fabric, foam, gel, or memory foam.

This word is commonly used in everyday domestic, office, and transportation contexts — for example, when buying accessories for dining chairs, office ergonomics, or motorcycle gear. It’s neutral in register and appropriate for both spoken and written Chinese. While 座 can also mean 'a measure word for large objects' (e.g., 一座山), in 座垫 it functions strictly as a semantic component indicating seating function, not as a classifier.