A capsule is a small container, usually with rounded ends, that holds something inside. The most common type is a medicine capsule: a tiny cylinder made of gelatin that dissolves in your stomach, releasing the medicine it contains. Doctors prescribe capsules when the medicine inside tastes bad or needs to reach your stomach before it starts working.

The word also describes other small, enclosed containers. A time capsule is a box filled with objects from today, then buried or sealed away for people in the future to discover. Schools sometimes create time capsules with student photos, newspapers, and popular toys, then open them decades later. A space capsule is the small, protective compartment where astronauts sit during launch and reentry. The early Mercury and Apollo space capsules were barely larger than a phone booth, yet they carried astronauts safely through the dangers of space travel.

Whether it's protecting medicine, preserving memories, or shielding astronauts, a capsule's job is to keep its contents safe inside a compact, sealed space until the right moment arrives.