umbra

[ uhm-bruh ]

/ ˈʌm brə /

SEE MORE SYNONYMS FOR umbra ON THESAURUS.COM

noun, plural um·bras, um·brae [uhm-bree] /ˈʌm bri/.

shade; shadow.

the invariable or characteristic accompaniment or companion of a person or thing.

Astronomy.

the complete or perfect shadow of an opaque body, as a planet, where the direct light from the source of illumination is completely cut off.Compare penumbra(def 1a).
the dark central portion of a sunspot.Compare penumbra(def 1b).

a phantom or shadowy apparition, as of someone or something not physically present; ghost; spectral image.

Nearby words

umble pie, umbles, umbo, umbonal, umbonate, umbra, umbrage, umbrageous, umbrella, umbrella bird, umbrella leaf

Origin of umbra

1590–1600; < Latin: shade, shadow

Related forms

um·bral, adjective

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for umbra

From the fact that the spectrum is darkened we learn that there is considerable general absorption of light in the umbra.
The Story of the Heavens|Robert Stawell Ball
The double of the Egyptian sepulchral records corresponds exactly to the of the Greeks and the umbra of the Latins.
A history of art in ancient Egypt, Vol. I (of 2)|Georges Perrot
Sed nos veri iuris germanaeque iustitiae solidam et expressam effigiem nullam tenemus, umbra et imaginibus utimur.
De Officiis|Marcus Tullius Cicero
Within the umbra there is sometimes seen a still darker spot, called the nucleus.
The Astronomy of Milton's 'Paradise Lost'|Thomas Orchard

Each spot is quite sharply divided into an umbra and a penumbra.
Astronomy for Young Folks|Isabel Martin Lewis

British Dictionary definitions for umbra

umbra

/ (ˈʌmbrə) /

noun plural -brae (-briː) or -bras

a region of complete shadow resulting from the total obstruction of light by an opaque object, esp the shadow cast by the moon onto the earth during a solar eclipse

the darker inner region of a sunspot

Compare penumbra

Derived Forms

umbral, adjective

Word Origin for umbra

C16: from Latin: shade, shadow

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Science definitions for umbra

umbra

[ ŭm′brə ]

Plural umbras umbrae (ŭm′brē)

The darkest part of a shadow, especially the cone-shaped region of full shadow cast by Earth, the Moon, or another body during an eclipse. In a full lunar eclipse, which generally lasts for one or two hours, the entire disk of the Moon is darkened as it passes through the umbra. During this period the Moon takes on a faint reddish glow due to illumination by a small amount of sunlight that is refracted through the Earth's atmosphere and bent toward the darkened Moon; the reddish tint is caused by the filtering out of blue wavelengths as the sunlight passes through the Earth's atmosphere, leaving only the longer wavelengths on the red end of the spectrum. See Note at eclipse.

The dark central region of a sunspot. Compare penumbra.