Impervious to light; excluding the light perfectly. Compare air-tight.
The Century Dictionary (Public Domain)
Use "light-tight" in a sentence
"For each of the four evening experimental sessions, Dr. Creath and I placed four germanium leaves, as well as four geranium flowers, in a completely dark, light-tight chamber that was housed in a light-tight darkroom."
"After collecting thirty minutes of baseline data, we invited the respective angels to enter the light-tight chamber for thirty minutes."
"Both cameras can register single photons of light on their supersensitive CCD digital arrays; both can be programmed to take long-exposure pictures in completely darkened spaces in light-tight chambers and rooms over minutes or even hours."