penumbra

• POS: Noun
• HYPHEN: pe=num=bra

CIDE DICTIONARY

penumbra, n. [NL., fr. L. paene almost + umbra shade.].

•  An incomplete or partial shadow.  [1913 Webster]
•  The shadow cast, in an eclipse, where the light is partly, but not wholly, cut off by the intervening body; the space of partial illumination between the umbra, or perfect shadow, on all sides, and the full light.  Sir I. Newton.  [1913 Webster]

  " The faint shade surrounding the dark central portion of a solar spot is also called the penumbra, and sometimes umbra."  [1913 Webster]
•  The part of a picture where the shade imperceptibly blends with the light.  [1913 Webster]

OXFORD DICTIONARY

penumbra, n. (pl. penumbrae or penumbras)
1 a the partly shaded region around the shadow of an opaque body, esp. that around the total shadow of the moon or earth in an eclipse. b the less dark outer part of a sunspot.
2 a partial shadow.

Derivative

penumbral adj.

Etymology

mod.L f. L paene almost + UMBRA shadow

ROGET THESAURUS

penumbra

Darkness

N darkness, absence of light, blackness, obscurity, gloom, murk, dusk, Cimmerian darkness, Stygian darkness, Egyptian darkness, night, midnight, dead of night, witching hour of night, witching time of night, blind man's holiday, darkness visible, darkness that can be felt, palpable obscure, Erebus, the jaws of darkness, sablevested night, shade, shadow, umbra, penumbra, sciagraphy, obscuration, occultation, adumbration, obumbration, obtenebration, offuscation, caligation, extinction, eclipse, total eclipse, gathering of the clouds, shading, distribution of shade, chiaroscuro, noctivagation, black body, hohlraum, black hole, dark star, dark matter, cold dark matter, dark, darksome, darkling, obscure, tenebrious, sombrous, pitch dark, pitchy, pitch black, caliginous, black, sunless, lightless &c (sun) (light), somber, dusky, unilluminated &c (illuminate), nocturnal, dingy, lurid, gloomy, murky, murksome, shady, umbrageous, overcast, cloudy, darkened, dark as pitch, dark as a pit, dark as Erebus, benighted, noctivagant, noctivagous, in the dark, in the shade, brief as the lightning in the collied night, eldest Night and Chaos, ancestors of Nature, the blackness of the noonday night, the prayer of Ajax was for light.