袋子 (dài zi) is a general, neutral term for 'bag' — any flexible container used to hold, carry, or store items. The character 袋 (dài) originally referred to a cloth sack with a drawstring, and 子 (zi) is a common nominal suffix that turns the root into a concrete noun. Together, they form a standard, everyday word applicable to many types of bags: plastic shopping bags, cloth tote bags, paper lunch bags, or even small pouches.

Unlike more specific terms like 包 (bāo, 'handbag' or 'backpack') or 书包 (shūbāo, 'school backpack'), 袋子 emphasizes function over form and is rarely used for rigid containers like boxes or suitcases. It appears frequently in daily life — at supermarkets, markets, pharmacies, and homes — and is often paired with measure words like 个 (gè) or 只 (zhī). While it can refer to anatomical 'sacs' in technical contexts (e.g., 茶叶袋, 'tea bag'), its core meaning remains functional and colloquial.