Part of speech: noun
Origin: Latin, mid-17th century
The partially illuminated outer part of a shadow created by a solid object
The outlying, fringe area in which a condition exists to a lesser degree
Examples of Penumbra in a sentence
"The shadow of the moon cast a hazy penumbra over a swath of Earth during the partial eclipse."
"The sunlight coming through the curtains created a penumbra on the rug in contrast to the solid wall."
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A penumbra creates a hazy outlying region where an object doesn't cast such a heavy shadow. As a result, the incomplete region of the object's shadow might appear like an ephemeral halo around its darker, more solid region.
Did you Know?
Penumbra comes from the fused Latin roots of paene-, meaning "almost," and umbra, meaning "shadow." The resulting definition gives us an "almost shadow."