penumbra
noun
Edward EgglestonJames Atlas
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Every solar eclipse casts an umbra, the darker central area in which almost no light reaches the earth, and a penumbra, the area of partial shadow where part of the sun is still visible. Penumbra can thus be used to describe any "gray area" where things aren't all black and white. For example, the right to privacy falls under the penumbra of the U.S. Constitution; though it isn't specifically guaranteed there, the Supreme Court has held that it is implied, and thus that the government may not intrude into certain areas of a citizen's private life. Because its existence is still shadowy, however, the Court is still determining how much of an individual's life is protected by the right to privacy.
Examples of penumbra in a Sentence
Sara Holdren, Vulture, 7 Nov. 2024
The Tesla brand has always been in the shadow of its owner Elon Musk, and more recently that has not been such a positive penumbra for some.
—James Morris, Forbes, 19 Oct. 2024
Lacking this, other than emanations and penumbras, how exactly are bond prices supposed to measure NRSRO ratings in basis points?
—Barnet Sherman, Forbes, 17 Sep. 2024
The moon will begin entering Earth’s outer shadow, known as the penumbra, at 8:41 p.m. Eastern time, according to NASA.
—Sarah Kuta, Smithsonian Magazine, 13 Sep. 2024
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Cite this Entry
“Penumbra.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/penumbra. Accessed 28 Nov. 2024.
Copy CitationKids Definition
penumbra
noun
Medical Definition
penumbra
noun
Legal Definition
penumbra
noun
Griswold v. Connecticut, 381 U.S. 479 (1965) 
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