abumbral
adj. C2 Proficiency abum·bral
adj. relating to the dark part of a shadow or the area where something is completely hidden from light.
adj. relating to the darkest part of a shadow or the region where an object is entirely obscured from a light source. Often used in astronomical or geological contexts.
The abumbral region of the moon was completely dark.
During the total solar eclipse, the abumbral shadow of the moon blocked all sunlight from reaching the Earth's surface.
The researchers mapped the abumbral zones of the crater to determine how much of the interior remained permanently in darkness and thus potentially harbored ice deposits.