Swollen means enlarged or puffed up beyond normal size, usually because of fluid, air, or inflammation building up inside. When you twist your ankle playing soccer, it often becomes swollen: the injured area grows larger, tighter, and puffy as your body sends extra fluid there to begin healing. A mosquito bite swells up into an itchy bump. After dental surgery, your cheek might look swollen for a few days.

Rivers and streams can also become swollen after heavy rain, rising higher and faster than usual as extra water rushes through them. A swollen river might overflow its banks.

The word can describe anything unnaturally enlarged. A swollen balloon is stretched tight with air. Wood left in water becomes swollen as it absorbs moisture and expands. You might even hear someone say their book collection has swollen to fill three bookcases, meaning it has grown much larger over time.

Notice that swollen usually suggests something temporary. The ankle shrinks back to normal as it heals. The river returns to its usual level. The word captures that state of being bigger than usual, stretched beyond the ordinary, and waiting to return to normal size.