Definitions

1. noun

relating to or resembling a shadow or shade, especially one that is dark or ominous

“The umbral cloud cast a dark shadow over the entire landscape.”

2. adjective

of or relating to a shadow or shade

“The umbral areas of the forest were difficult to navigate.”

3. noun

a period or region of time during which the Moon is in a state of partial eclipse

“During the umbral eclipse, the Moon passed through the Earth’s shadow.”

4. noun

a part of a thing that is not clearly defined or visible

“The umbral region of the nebula was unclear, but scientists were working to map it.”