To moisten means to make something slightly wet or damp. When you moisten a sponge before wiping down a counter, you're adding just enough water to make it useful without creating puddles. When a baker moistens the edges of pie dough before pressing them together, they're adding a light coating of water to help the pieces stick.

The word suggests adding a small amount of liquid, not soaking or drenching. Your eyes naturally moisten themselves to stay comfortable and protected. On a dry winter day, you might moisten your lips with your tongue or use lip balm to keep them from getting chapped. A gardener might moisten the soil around seeds, giving them just enough water to sprout without drowning them.

Moisten often appears in recipes and instructions: “Moisten the cloth before cleaning the screen” or “Moisten your hands before shaping the dough.” It's about finding the right amount of wetness for the task. Too dry and the sponge won't clean well or the pie crust won't seal; too wet and you've got a different problem entirely. The related adjective is moist, which describes something that has been moistened or is naturally damp to the touch.