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the part of a shadow in which there is no light from any light source.
a sharp appearance to the edges of a structure on a radiograph.


radiology An image with sharply defined margins.


(ŭm′bră) [L., shade, shadow]
The edge of the radiographic image proper.


1. Region of very low illumination on a dark background.
2. Zone in which the brightness varies from some illumination to zero (umbra) in the shadow cast by an opaque object intercepting light from an extensive light source. See shadow.
References in periodicals archive ?
Not only did these experiences affect his poetry--and, through it, other Umbra writers'--they also set Dent's course for many years to come.
This step climbs up from the fundamental plane where the umbra meets the Earth to the culminating bulge of the globe and then goes down to the fundamental plane at umbral exit.
While he said Umbra has no plans to open a huge chain of stores, other flagship sites are a possibility.
1936 June 5 Full Moon, no eclipse 1955 June 5 penumbral lunar eclipse *1974 June 4 partial eclipse in the umbra *1993 June 4 total eclipse in the umbra *2012 June 4 partial eclipse in the umbra 2031 June 5 penumbral lunar eclipse 2050 June 5 Full Moon, no eclipse
TORONTO -- Umbra Hill open its first retail concept store here in the spring.
He participated in such crucial cultural/political institutions as Umbra, the Black Arts Repertory Theatre and School, the Revolutionary Action Movement, the Student Non-Violent Coordinating Committee, The Liberator, The Journal of Black Poetry, and Black Dialogue.
Umbra Software's Umbra[TM] middleware is the industry-standard occlusion culling solution.
Contract notice: Framework agreement for the supply of electricity and related services to the valle umbra servizi spa.
We remain hopeful that the Moro Islamic Liberation Front (MILF) will be able to resolve this internal situation [with renegade commander Ameril Umbra Kato] and that by doing so the peace process can move forward," President Benigno Aquino's spokesman Edwin Lacierda told the Star.
Besides Casabella and Umbra, the retailer has done co-branded mailings with OXO, simplehuman, Iris and 3M.
One of the coolest new card games is by Umbra, with cards cut in whimsical shapes - dog bones and fish - and packaged in colorful plastic card cases called Bow Wow and Splish Splash so they won't get wet at the beach or camp.
Specifically, he offers extended discussions of the writers at Howard University who published Dasein, Russell Atkins's Cleveland-based Free Lance, and New York's Umbra Poets.