- a shadowy, indefinite, or marginal area.
Origin of penumbra
Examples from the Web for penumbral
Historical Examples of penumbral
The line between the real and imaginary is vague and penumbral to us.Hills and the Sea
It may be that all the elements of the penumbral cone intersect the earth.
Isabel snuck into the guest bedroom and settled into an overstuffed armchair at a penumbral corner.The Capgras Shift
Strange, penumbral, characters roam the boardrooms of banks in the countries in transition.After the Rain
The penumbral line is marked from hour to hour on the maps given annually in the American Ephemeris.
- a fringe region of half shadow resulting from the partial obstruction of light by an opaque object
- astronomy the lighter and outer region of a sunspot
- painting the point or area in which light and shade blend
Word Origin for penumbra
Word Origin and History for penumbral
1660s, from Modern Latin penumbra "partial shadow outside the complete shadow of an eclipse," coined 1604 by Kepler from Latin pæne "almost" + umbra "shadow" (see umbrage). Related: Penumbral.
- A partial shadow between regions of full shadow (the umbra) and full illumination, especially as cast by Earth, the Moon, or another body during an eclipse. During a partial lunar eclipse, a portion of the Moon's disk remains within the penumbra of Earth's shadow while the rest is darkened by the umbra. See Note at eclipse.
- The grayish outer part of a sunspot. Compare umbra.