Shake means to move quickly back and forth or up and down. When you shake a bottle of salad dressing, you're mixing the oil and vinegar by moving the bottle rapidly in different directions. When a wet dog shakes itself after a bath, it's vibrating its whole body to fling off water. You might shake someone's hand as a greeting, moving it up and down in a friendly gesture.

Things can shake on their own, too. An earthquake shakes the ground. A washing machine shakes during the spin cycle. When you're cold or nervous, your body might shake involuntarily, which we call shivering or trembling.

A shake can also be a thick, sweet drink made by blending ice cream with milk, like a chocolate shake or strawberry shake.

The word appears in many expressions. If something happens in two shakes (or two shakes of a lamb's tail), it happens very quickly. When you shake things up, you make big changes to how something works. If you shake off a worry or a cold, you get rid of it. And when you shake on it, you're sealing an agreement with a handshake, showing that your word is solid and you'll follow through.