Penumbral (noun) Definition, Meaning & Examples

adjective

of, causing, or being the partial shadow outside the complete shadow of an opaque body, such as a planet, where the light from the source of illumination is only partly cut off:Four consecutive total lunar eclipses in a row, without any penumbral eclipses in between, are known as a tetrad.
relating to or being the grayish marginal portion of a sunspot:An average eye can see a sunspot with a penumbral diameter of at least 41 arcseconds.

relating to or being a shadowy, indefinite, or marginal area:The apple trees provide penumbral lighting that is perfect for studying, thinking, or even a nap.While the beneficiaries of corruption fête themselves with cocktail nights and caviar dreams, its victims wander a penumbral existence.
of or relating to the set of rights implicit in the U.S. Constitution or Bill of Rights:The wealthy, like everyone else, are entitled to the full enjoyment of the Constitution's express and penumbral guarantees.