To daydream means to let your mind wander into pleasant thoughts and imaginary scenes while you're awake. During a daydream, you might picture yourself scoring the winning goal in a championship game, imagine what it would be like to explore a distant planet, or replay a fun conversation with a friend. Your eyes might be open, staring at your math worksheet or out the classroom window, but your thoughts are somewhere else entirely.

Everyone daydreams. Your brain naturally drifts when you're doing something boring or automatic, like folding laundry or waiting in line. Sometimes daydreams help you work through problems or rehearse for future situations. A musician might daydream about performing at a concert, mentally practicing each note. An inventor might daydream about how a new creation could work.

The word can also be a noun: “I was lost in a daydream about summer vacation.” Unlike night dreams during sleep, which you can't control, daydreams are yours to direct. You can steer them toward whatever interests you. Teachers sometimes say “stop daydreaming and pay attention,” but daydreaming isn't always bad. Some of humanity's best ideas started as someone's daydream. Albert Einstein famously daydreamed about riding on a beam of light, which helped him develop the theory of relativity.