penumbra

Meanings

Plural: penumbrae, penumbras, penumbræ

Noun

• a fringe region of partial shadow around an umbra
• A partially shaded area around the edges of a shadow, especially an eclipse.
• A region around the edge of a sunspot, darker than the sun's surface but lighter than the middle of the sunspot.
• An area of uncertainty or intermediacy between two mutually exclusive states or categories.
• An area that lies on the edge of something; a fringe.
• Something related to, connected to, and implied by, the existence of something else that is necessary for the second thing to be full and complete in its essential aspects.
• A region of the brain that has lost only some of its blood supply, and retains structural integrity but has lost function.

Synonyms

grey area, outskirt, periphery