To doze means to sleep lightly for a short time, usually without meaning to. When you doze off during a long car ride, you're not deeply asleep like you are at night in your bed. You're hovering in that drowsy space between being awake and asleep, where sounds might still reach you faintly and you could wake up easily if someone said your name.

People often doze in places where they didn't plan to sleep: on the couch while watching TV, in a sunny spot while reading, or in class after staying up too late the night before. Your grandfather might doze in his armchair after Sunday dinner, his book sliding off his lap. A cat dozes on a windowsill, ears still twitching at interesting sounds outside.

Unlike taking a proper nap, which you do on purpose, dozing just happens when you're comfortable and tired. You might catch yourself dozing and jerk awake, momentarily confused about where you are. That light, accidental quality is what makes dozing different from sleeping or napping. When you doze, sleep sneaks up on you gently, like fog rolling in.