The ratio of visible light transmitted through a substance to the total visible light incident on its surface.
The percentage of light that is transmitted through glass in the visible light spectrum (380 to 720 nanometers). The higher the number the higher the percentage of visible light transmitted through the window.
The percentage of visible light (380 - 780 nanometers) that is transmitted through the glass. (Visible light is the only portion of the solar spectrum visible to the human eye.)
The amount of visible light that passes through the glazing material of a window, expressed as a percentage.