penumbra

play
noun pen·um·bra \pə-ˈnəm-brə\

Definition of penumbra

plural

penumbrae

play \-(ˌ)brē, -ˌbrī\ or

penumbras

  1. 1 a :  a space of partial illumination (as in an eclipse) between the perfect shadow on all sides and the full light b :  a shaded region surrounding the dark central portion of a sunspot

  2. 2 :  a surrounding or adjoining region in which something exists in a lesser degree :  fringe

  3. 3 :  a body of rights held to be guaranteed by implication in a civil constitution

  4. 4 :  something that covers, surrounds, or obscures :  shroud <a penumbra of secrecy> <a penumbra of somber dignity has descended over his reputation — James Atlas>

penumbral

play \-brəl\ adjective

Examples of penumbra in a sentence

  1. <the lunar eclipse began with a subtle darkening of the lunar surface as it passed within the Earth's penumbra>

  2. <a penumbra of despair fell over the doomed city>

Did You Know?

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.

Origin and Etymology of penumbra

New Latin, from Latin paene almost + umbra shadow — more at umbrage


First Known Use: 1665

Other Astronomy Terms


Medical Dictionary

penumbra

play
noun pe·num·bra \pə-ˈnəm-brə\

Medical Definition of penumbra

plural

penumbrae

\-(ˌ)brē, -ˌbrī\play play or

penumbras

  1. :  a blurred area in a radiograph at the edge of an anatomical structure

penumbral

\-brəl\play adjective

Law Dictionary

penumbra

play
noun pe·num·bra \pi-ˈnəm-brə\

Legal Definition of penumbra

plural

penumbras

  1. 1 :  an area within which distinction or resolution is difficult or uncertain <the public-private penumbra>

  2. 2 :  an extension of protection, reach, application, or consideration; especially :  a body of rights held to be guaranteed by implication from other rights explicitly enumerated in the U.S. Constitution <the First Amendment has a penumbra where privacy is protected from governmental intrusion — Griswold v. Connecticut, 381 U.S. 479 (1965)> — see also Griswold v. Connecticut

penumbral

\-brəl\ play adjective

Learn More about penumbra


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