1. the quality or state of giving off or reflecting light; luminosity
2. the quality of being vivid or intense in color
3. intelligence or mental sharpness

Examples

• The brightness of the sun made it difficult to see without sunglasses.
• She adjusted the brightness on her computer screen.
• The brightness of the yellow paint made the room feel more cheerful.
• His brightness in mathematics impressed all his teachers.
• The child’s brightness and enthusiasm lifted everyone’s spirits.
• The brightness of the stars was remarkable in the clear night sky.
• The brightness of her smile could light up any room.