penumbra
[ pi-nuhm-bruh ]
/ pɪˈnʌm brə /
noun, plural pe·num·brae [pi-nuhm-bree] /pɪˈnʌm bri/, pe·num·bras.
Astronomy.
- the partial or imperfect shadow outside the complete shadow of an opaque body, as a planet, where the light from the source of illumination is only partly cut off.Compare umbra(def 3a).
- the grayish marginal portion of a sunspot.Compare umbra(def 3b).
a shadowy, indefinite, or marginal area.
Origin of penumbra
OTHER WORDS FROM penumbra
pe·num·bral, pe·num·brous, adjectiveWords nearby penumbra
pentylenetetrazol,
penuche,
penuchle,
penult,
penultimate,
penumbra,
penurious,
penury,
penutian,
penza,
penzance
Example sentences from the Web for penumbra
British Dictionary definitions for penumbra
penumbra
/ (pɪˈnʌmbrə) /
noun plural -brae (-briː) or -bras
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
Compare
umbra
Derived forms of penumbra
penumbral or penumbrous, adjectiveWord Origin for penumbra
C17: via New Latin from Latin
paene almost +
umbra shadow
Scientific definitions for penumbra
penumbra
[ pĭ-nŭm′brə ]
Plural penumbras penumbrae (pĭ-nŭm′brē)
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.