Milky describes something that looks like milk: white or pale, cloudy, and not clear. A glass of water might turn milky when you stir chalk dust into it. The night sky can look milky on humid evenings when moisture in the air softens the stars. Certain gemstones, like moonstones or opals, have a milky quality that makes them seem to glow softly from within rather than sparkle sharply like diamonds.

The word also describes things that contain milk or taste like milk. Hot chocolate made with lots of milk tastes milky and creamy. Some teas, like chai, are often served milky, with milk or cream added.

Our own galaxy is called the Milky Way because on dark nights, far from city lights, it looks like a pale, cloudy river of light stretching across the sky. When you look up at it, you're actually seeing the combined light of billions of stars too far away to see individually, all blending together into that characteristic milky glow.

The word can also describe behavior or attitudes that are weak or timid, though this usage is less common and can be unkind.