Definition of Penumbra
1. Noun. A fringe region of partial shadow around an umbra.
Definition of Penumbra
1. n. An incomplete or partial shadow.
Definition of Penumbra
1. a partial shadow [n -BRAE or -BRAS]
Medical Definition of Penumbra
1.
1. An incomplete or partial shadow.
2. 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.
The faint shade surrounding the dark central portion of a solar spot is also called the penumbra, and sometimes umbra.
3. The part of a picture where the shade imperceptibly blends with the light.
Origin: NL, fr. L. Paene almost + umbra shade.
Source: Websters Dictionary
(01 Mar 1998)
Lexicographical Neighbors of Penumbra
Other Resources:
