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umbra
This term describes the absolute center of a shadow where the light source is entirely obscured. It carries a clinical, scientific connotation, typically appearing in astronomical or optical contexts to distinguish the total darkness from the penumbra, which is the lighter, partial shadow surrounding it.
In solar physics, the word specifically identifies the cool, dark core of a sunspot. Because it refers to a specific geometric or physical region of a shadow, it is used in technical descriptions of eclipses and celestial alignments rather than in casual descriptions of shade.
Meanings
Examples
The moon cast a narrow umbra across the surface of the Earth.
Look at the telescope and you can see the dark umbra of the sunspot.
I wonder if I am standing in the umbra or just the penumbra.
During a total solar eclipse the observer must be within the umbra.
The umbra is the region where the light source is completely obscured.
Ancient astronomers struggled to define the exact shape of the umbra.
The central umbra of the sunspot appears almost black compared to the photosphere.
Wait until the umbra reaches this coordinate for the total blackout.