Definitions

1. noun

A partial shadow or area of partial shadow, especially the region of a solar eclipse visible from a given point on the Earth.

“The penumbra of the eclipse was visible for several hours before the total eclipse began.”

2. plural noun

The penumbral region of a partial solar eclipse, or the penumbral regions of a series of partial solar eclipses.

“The penumbrae of the past decade have been fascinating to study and observe.”