Quick definitions (penumbra)
noun: a fringe region of partial shadow around an umbra

Etymology: New Latin, from Latin paene almost + umbra shadow -- more at UMBRAGE
1 a : a space of partial illumination (as in an eclipse) between the perfect shadow on all sides and the full light b : a shaded region surrounding the dark central portion of a sunspot


2 : a surrounding or adjoining region in which something exists in a lesser degree : FRINGE
3 : a body of rights held to be guaranteed by implication in a civil constitution
4 : something that covers, surrounds, or obscures : SHROUD <a penumbra of secrecy> <a penumbra of somber dignity has descended over his reputation -- James Atlas>
- pen·um·bral /-br&l/ adjective