To make or become less heavy or burdensome. She decided to lighten her load by donating some of her old clothes.
To make or become brighter or more illuminated. The new lamp will lighten the room considerably.
To make or become less serious or more cheerful. He tried to lighten the mood with a joke.
To reduce the weight of something, especially by removing some of its contents. They lightened the ship by throwing some cargo overboard.
To make or become lighter in color or shade. The fabric will lighten after several washes.