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penumbra

play
noun pen·um·bra \pə-ˈnəm-brə\

Definition of penumbra

plural pen·um·braeplay \-(ˌ)brē, -ˌbrī\ or pen·um·bras

  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>

pen·um·bral play \-brəl\ adjective


Examples of penumbra

  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>



Origin 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 pe·num·brae \-(ˌ)brē, -ˌbrī\play play or pe·num·bras

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

  2. pe·num·bral \-brəl\play adjective




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