The word turn has several common meanings:

1. To rotate or change direction. When you turn a doorknob, you twist it. When a car turns left, it changes from going straight to going in a new direction. A dancer might turn in circles, spinning on one foot. The Earth turns on its axis, giving us day and night.
2. A chance or opportunity to do something, especially when people are taking turns in order. In a board game, you wait for your turn to roll the dice. At recess, kids might take turns on the swing set. A turn can also mean a specific period when someone is responsible for something, like when it's your turn to feed the dog or wash the dishes.
3. To change from one state or condition to another. Leaves turn red and gold in autumn. Milk turns sour if left out too long. A caterpillar turns into a butterfly. Someone's luck might turn from bad to good. When water gets cold enough, it turns to ice.

The word appears in many expressions. A good turn means a helpful act, as in “one good turn deserves another.” When something happens at every turn, it happens constantly. If you turn up somewhere, you arrive or appear. And when something takes an unexpected turn, it changes in a surprising way.