胶囊 (jiāo náng) literally means 'glue pouch' — 胶 (jiāo) refers to glue or gelatin, and 囊 (náng) means 'sac', 'pouch', or 'bag'. In modern usage, it specifically denotes a small, soft or hard gelatin-based container used to enclose medicine, vitamins, or supplements. These capsules are designed to dissolve in the stomach or intestines, releasing their contents gradually or protecting sensitive ingredients from stomach acid.

The word is commonly heard in pharmacies, hospitals, and health-related conversations. It’s a neutral, formal term used across spoken and written Chinese — you’ll see it on medicine packaging, prescriptions, and health articles. While originally derived from the material (gelatin), today’s capsules may be made from plant-based alternatives, but the name remains unchanged. It’s never used for non-medical containers like pill organizers or blister packs — those have different terms.