Umbra - Definitions from Dictionary.com

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Dictionary.com Unabridged (v 1.1) - Cite This Source - Share This

um·bra

Audio Help [uhm-bruh] Pronunciation Key

–noun, plural -bras, -brae

Audio Help [-bree] Pronunciation Key.

1.	shade; shadow.

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

Astronomy.

a.	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).

b.	the dark central portion of a sunspot. Compare penumbra (def. 1b).

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

[Origin: 1590–1600; < L: shade, shadow

]

—Related forms

umbral, adjective

Dictionary.com Unabridged (v 1.1)
Based on the Random House Unabridged Dictionary, © Random House, Inc. 2006.

Encyclopædia Britannica, Inc.
Umbra

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American Heritage Dictionary - Cite This Source - Share This

um·bra Audio Help (ŭm'brə) Pronunciation Key
n. pl. um·bras or um·brae (-brē)

A dark area, especially the blackest part of a shadow from which all light is cut off. See Synonyms at shade.
Astronomy
1. The completely dark portion of the shadow cast by the earth, moon, or other body during an eclipse.
2. The darkest region of a sunspot.

[Latin, shadow.]

um'bral adj.

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The American Heritage® Dictionary of the English Language, Fourth Edition
Copyright © 2006 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.

Online Etymology Dictionary - Cite This Source - Share This
umbra

1599, "phantom, ghost," a fig. use from L. umbra "shade, shadow" (see umbrage). Astronomical sense of "shadow cast by the earth or moon during an eclipse" is first recorded 1679. Meaning "an uninvited guest accompanying an invited one" is from 1696.

WordNet - Cite This Source - Share This

umbra
noun
a region of complete shadow resulting from total obstruction of light

The American Heritage Science Dictionary - Cite This Source - Share This

umbra Audio Help (ŭm'brə) Pronunciation Key
Plural umbras or 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.

The American Heritage® Science Dictionary
Copyright © 2002 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.

Webster's Revised Unabridged Dictionary - Cite This Source - Share This

Umbra

Mud\, n. [Akin to LG. mudde, D. modder, G. moder mold, OSw. modd mud, Sw. modder mother, Dan. mudder mud. Cf. Mother a scum on liquors.] Earth and water mixed so as to be soft and adhesive.

Mud bass (Zo["o]l.), a fresh-water fish (Acantharchum pomotis) of the Eastern United States. It produces a deep grunting note.

Mud bath, an immersion of the body, or some part of it, in mud charged with medicinal agents, as a remedy for disease.

Mud boat, a large flatboat used in deredging.

Mud cat. See Catfish.

Mud crab (Zo["o]l.), any one of several American marine crabs of the genus Panopeus.

Mud dab (Zo["o]l.), the winter flounder. See Flounder, and Dab.

Mud dauber (Zo["o]l.), a mud wasp.

Mud devil (Zo["o]l.), the fellbender.

Mud drum (Steam Boilers), a drum beneath a boiler, into which sediment and mud in the water can settle for removal.

Mud eel (Zo["o]l.), a long, slender, aquatic amphibian (Siren lacertina), found in the Southern United States. It has persistent external gills and only the anterior pair of legs. See Siren.

Mud frog (Zo["o]l.), a European frog (Pelobates fuscus).

Mud hen. (Zo["o]l.) (a) The American coot (Fulica Americana). (b) The clapper rail.

Mud lark, a person who cleans sewers, or delves in mud. [Slang]

Mud minnow (Zo["o]l.), any small American fresh-water fish of the genus Umbra, as U. limi. The genus is allied to the pickerels.

Mud plug, a plug for stopping the mudhole of a boiler.

Mud puppy (Zo["o]l.), the menobranchus.

Mud scow, a heavy scow, used in dredging; a mud boat. [U.S.]

Mud turtle, Mud tortoise (Zo["o]l.), any one of numerous species of fresh-water tortoises of the United States.

Mud wasp (Zo["o]l.), any one of numerous species of hymenopterous insects belonging to Pep[ae]us, and allied genera, which construct groups of mud cells, attached, side by side, to stones or to the woodwork of buildings, etc. The female places an egg in each cell, together with spiders or other insects, paralyzed by a sting, to serve as food for the larva. Called also mud dauber.

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UMBRA

UMBRA: in Acronym Finder

On-line Medical Dictionary - Cite This Source - Share This

umbra

umbra: in CancerWEB's On-line Medical Dictionary

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