'塑料袋' (sù liào dài) literally means 'plastic + material + bag' — a compound noun where 塑料 (plastic) functions as a modifier describing the material of the 袋 (bag). It refers specifically to thin, flexible bags commonly made from polyethylene or similar synthetic polymers, used for carrying groceries, packaging goods, or storing items. These bags are ubiquitous in daily life across China and other Chinese-speaking regions.

While convenient, plastic bags are increasingly regulated due to environmental concerns — many cities now charge for them or ban single-use versions. The term is neutral in register and widely understood in both formal and informal contexts, though it carries subtle connotations of disposability and ecological impact. It does not refer to thicker reusable shopping bags (which are often called '环保袋' — eco-bags) or paper bags.