Citrus refers to a family of juicy, often tangy fruits that grow on trees in warm climates. Oranges, lemons, limes, and grapefruits are all citrus fruits. They share certain traits: thick, pebbly peels that release fragrant oils when you scratch them, juicy segments inside, and that distinctive sharp or sweet-sour taste.

What makes citrus fruits special is their high vitamin C content, which helps keep people healthy. Sailors on long ocean voyages used to get a terrible disease called scurvy from lack of vitamin C, until they discovered that bringing citrus fruits aboard prevented it. British sailors carried so many limes that Americans started calling them “limeys.”

Citrus trees are evergreen, meaning they keep their leaves year-round, and they produce fragrant white blossoms before the fruit appears. The trees originally came from Southeast Asia but now grow in places like Florida, California, Spain, and Brazil. When you see citrus groves stretching across a warm landscape, you're looking at orchards filled with these valuable fruit trees.

The word citrus also describes the bright, tangy flavor or scent of these fruits. A cleaning product might have a fresh citrus smell, or a recipe might call for adding citrus zest (tiny shavings of the flavorful peel).