'Penumbra' definitions:

Definition of 'penumbra'

From: WordNet
noun
A fringe region of partial shadow around an umbra

Definition of 'Penumbra'

From: GCIDE
  • Penumbra \Pe*num"bra\, n. [NL., fr. L. paene almost + umbra shade.]
  • 1. An incomplete or partial shadow. [1913 Webster]
  • 2. (Astron.) The shadow cast, in an eclipse, where the light is partly, but not wholly, cut off by the intervening body; the space of partial illumination between the umbra, or perfect shadow, on all sides, and the full light. --Sir I. Newton. [1913 Webster]
  • Note: The faint shade surrounding the dark central portion of a solar spot is also called the penumbra, and sometimes umbra. [1913 Webster]
  • 3. (Paint.) The part of a picture where the shade imperceptibly blends with the light. [1913 Webster]

Definition of 'penumbra'

From: GCIDE
  • Penumbra \Pe*num"bra\, n. [NL., fr. L. paene almost + umbra shade.]
  • 1. An incomplete or partial shadow. [1913 Webster]
  • 2. (Astron.) The shadow cast, in an eclipse, where the light is partly, but not wholly, cut off by the intervening body; the space of partial illumination between the umbra, or perfect shadow, on all sides, and the full light. --Sir I. Newton. [1913 Webster]
  • Note: The faint shade surrounding the dark central portion of a solar spot is also called the penumbra, and sometimes umbra. [1913 Webster]
  • 3. (Paint.) The part of a picture where the shade imperceptibly blends with the light. [1913 Webster]