Penumbra

penumbra: [pi-nuhm-bruh] noun a space of partial illumination between the perfect shadow on all sides and the full light; a shadowy, indefinite, or marginal area. In other words, part of a shadow where the light source is only partially blocked. "Penumbra" is also the name of the surviving tissue at the margin of an ischemic event (such as a stroke) which is in danger of hypoxia and subsequent cell death, a French Gothic Metal band, and an episode of Star Trek: Deep Space Nine.