[pɪˈnʌmbrə], (Noun)

Definitions:
- the partially shaded outer region of the shadow cast by an opaque object

- a peripheral or indeterminate area or group
(e.g: an immense penumbra of theory surrounds any observation)


Phrases:

Origin:
mid 17th century: modern Latin, from Latin paene ‘almost’ + umbra ‘shadow’