umbral

[ uhm-bruhl ]

adjective

1. of or like a shadow or shadowy apparition:

   Smoke was rising and beginning to coat the clouds a deep, umbral black.

   In an instant the vampire’s corporeal form dematerialized into an umbral form that quickly merged with the surrounding cover of night.

2. Astronomy.
   1. relating to or being the complete shadow of an opaque body, such as a planet, where all direct light from the source of illumination is cut off: Compare penumbral 1a.

      It was to be a very deep eclipse, with the moon passing very close to the center of Earth's umbral shadow.

   2. relating to or being the dark central portion of a sunspot: Compare penumbral 1b.

      Umbral flashes—powerful brightenings that shock the darkest part of the sunspot—appear continuously every 2 to 3 minutes.

Word History and Origins

Origin of umbral¹

umbra ( def ) + -al ¹( def )

Example Sentences

Outside the umbral cone is that of the penumbra, within which the sun is partially hidden by the moon.

From Project Gutenberg

Rosario entraba una llave en la invisible cerradura, y abra cuidadosamente la 115 puerta en cuyo umbral se haban sentado.

From Project Gutenberg

Related Words

• dark
• ghostly
• shady