a region of complete shadow resulting from the total obstruction of light by an opaque object, esp the shadow cast by the moon onto the earth during a solar eclipse
2.
the darker inner region of a sunspot
Compare penumbra
Derived forms
umbral (ˈumbral)
adjective
Word origin
C16: from Latin: shade, shadow
umbra in American English
(ˈʌmbrə)
nounWord forms: pluralˈumbrae (ˈʌmbri) or ˈumbras
1.
shade or a shadow
2.
the dark central cone of shadow projecting from a planet or satellite on the side opposite the sun
3.
the dark central part of a sunspot
4. Rare
a phantom, or ghost
5. Physics
a perfect or complete shadow, in which no direct light is received from the source of illumination