penumbra
n. C2 Proficiency Oxford US //pɪˈnəmbɹə// UK //pˈɛnʌmbɹɐ// penum·bra
n. the lighter outer part of a shadow where only some of the light is blocked. You also use it to describe a secondary area or a group of things related to a central topic.
n. the partially shaded outer region of a shadow cast by an opaque object; a peripheral or marginal area where something exists to a lesser degree. Countable.
The moon moves into the penumbra during the early stages of the eclipse.
We could barely see the outlines of the trees standing in the penumbra of the streetlamp.
The legal ruling affects not only the direct participants but also an entire penumbra of related industries that rely on current intellectual property definitions for their operations.
From New Latin pēnumbra, from Latin paene (“almost”) + umbra (“shadow”).