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Definition of penumbra


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pe·num·bra  audio  (p-nmbr) KEY 

NOUN:
pl. pe·num·brae  (-br) KEY  or pe·num·bras
  1. A partial shadow, as in an eclipse, between regions of complete shadow and complete illumination. See Synonyms at shade.
  2. The grayish outer part of a sunspot.
  3. An area in which something exists to a lesser or uncertain degree: "The First Amendment has a penumbra where privacy is protected from governmental intrusion" (Joseph A. Califano, Jr.).
  4. An outlying surrounding region; a periphery: "Downtown Chicago and its penumbra also stand rejuvenated" (John McCormick).

ETYMOLOGY:
New Latin pnumbra : Latin paene, almost + Latin umbra, shadow

OTHER FORMS:
pe·numbral or pe·numbrous(Adjective)


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