1. to make or become lighter in weight
2. to make or become brighter or less dark
3. to make or become less serious, severe, or burdensome

Examples

• She lightens her backpack by removing unnecessary items.
• The sky lightens as dawn approaches.
• Adding windows lightens the dark room considerably.
• His joke lightens the tense atmosphere in the meeting.
• The sun lightens her hair during summer months.
• Exercise lightens my mood when I’m feeling stressed.
• The bleach lightens the fabric to a pale shade.