lux
n. C / U C2 Proficiency US //ˈɫəks// UK //lˈʌks// lux
n. a unit used to measure how much light falls on a surface. You use it to describe how bright a room or a screen is.
n. the SI unit of illuminance, equal to one lumen per square metre. Used to quantify the intensity of light as perceived by the human eye hitting a specific area.
The office lighting should be at least 500 lux for comfortable reading.
The technician used a light meter to ensure the film set reached the required lux for the camera sensors.
While a moonless night might provide only 0.0001 lux, a bright summer day can exceed 100,000 lux, demonstrating the incredible range of human visual adaptation.
Usage
The plural form is also 'lux'. Often used in technical specifications for cameras, projectors, and workplace safety standards.