To refrigerate something means to keep it cold in a refrigerator to preserve it and prevent it from spoiling. When you refrigerate milk, leftovers, or fresh vegetables, you're slowing down the growth of bacteria and mold that would otherwise make the food unsafe to eat.

Before refrigeration was invented in the early 1900s, people had to eat food quickly, preserve it with salt or smoke, or store it in cool cellars and icehouses. The ability to refrigerate food transformed daily life: families could buy groceries once a week instead of every day, and fresh foods could travel long distances without spoiling. A Florida orange can now reach a grocery store in Maine still fresh and delicious.

You'll often see instructions to refrigerate after opening on bottles and jars, which means the product stays fresh longer when kept cold once you've broken the seal. Some medications need to be refrigerated too, not just food. When something is refrigerated, it's being kept at temperatures usually between 32 and 40 degrees Fahrenheit, cold enough to preserve but not cold enough to freeze.