To tousle means to mess up someone's hair in a playful, affectionate way, making it stick up in different directions or look charmingly disheveled. When a dad tousles his daughter's hair after she scores a goal, he's ruffling it up as a gesture of pride and affection. When the wind tousles your hair on a breezy day, it leaves it looking windswept and wild.

The word suggests a casual, gentle kind of messiness, not the tangled chaos you get after forgetting to brush your hair for a long time. Tousled hair has a relaxed, carefree look. In stories, you might read about a character with tousled hair after waking up, or an athlete with tousled locks after removing their helmet.

While tousle most often describes hair, it can occasionally refer to anything playfully mussed up or disarranged, like tousled bedsheets or feathers on a bird. The word carries a sense of warmth and informality. People usually tousle the hair of someone they like; it's generally a friendly gesture.