Luminance
Brightness
noun
きど
光輝 (こうき) Brightness, Splendor
輝度 (きど) Luminance, Brightness
輝き (かがやき) Radiance
軌道 (きどう) Orbit, Trajectory
怒気 (どき) Anger, Fit Of Anger
Additional Luminance makes it easier to get a key き into a door ど
The kiddo きど had no idea what Luminance meant.