Sometimes we need an unnecessary and fancy word to describe the simplest of things.
Umbra is a word used to describe a shaded area and is the basis of words such as umbrella, penumbra and umbrage. It can also describe a conical shadow excluding all light from a given source and the center of sunspots (the dark spots you can see on the sun with special equipment.)
Some synonyms include: Shade, shadow, cover and adumbration.
Some antonyms include: Light and brightness
“Pulvis et umbra sumus. (We are but dust and shadow.)”
– Horace, The Odes of Horace: Biligual Edition.
“When the moon passes into the penumbra, it darkens the surface of the moon, making it look as if a ‘bite’ has been taken from the lunar surface. ‘Totality’ occurs when the moon is completely submerged in the umbra, and takes on a deep red hue.”
— Maria Rovito, The Snapper: Millersville University, April 9, 2015