the quality or state of giving out or reflecting light

we can change the brightness of the bulb

the comet's brightness had dimmed

the quality of being intelligent and quick-witted

he reminded me of my first son with his brightness and inquisitiveness

the quality of being cheerful or lively

there's so much light and brightness in their faces

the quality in sound of being clear, vibrant, and typically high-pitched

tone alters the brightness of the sound