umbra
An umbra is the darkest, innermost part of a shadow, specifically the area where a light source is completely blocked by an opaque object. Imagine standing directly behind a large building during a bright, sunny day; the point where the sun is entirely hidden from your view is the umbra. While it is a technical term used in astronomy—referring to the central part of an eclipse—it is often used in literature to describe a sense of total darkness, gloom, or a mysterious, encroaching presence. You will most commonly see it in scientific contexts or in descriptive, dramatic prose.
In conversation
Astronomy class
During a total solar eclipse, the moon's umbra touches the Earth's surface.
During a total solar eclipse, the moon's umbra touches the Earth's surface.
So that's why it gets completely dark for a few minutes?
So that's why it gets completely dark for a few minutes?
Used in its primary scientific sense.
Discussing a book
The author describes the villain as living in the umbra of the old castle.
The author describes the villain as living in the umbra of the old castle.
That sounds incredibly moody and ominous.
That sounds incredibly moody and ominous.
Used metaphorically to imply a dark, hidden domain.
Examples
The moon cast its umbra upon the path.
The moon cast its umbra upon the path.
Observers within the umbra experienced a total eclipse of the sun.
Observers within the umbra experienced a total eclipse of the sun.
She felt as though she were stepping out from the umbra of her father's long-standing reputation.
She felt as though she were stepping out from the umbra of her father's long-standing reputation.
