umbra

noun (plural umbras or umbrae /-briː/)

• 1the fully shaded inner region of a shadow cast by an opaque object, especially the area on the earth or moon experiencing the total phase of an eclipse. Compare with penumbra.
• Astronomy the dark central part of a sunspot.

• 2 [mass noun] literary shadow or darkness: an impenetrable umbra seemed to fill every inch of the museum