- 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.Compare umbral 2a.
- 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.Compare umbral 2b.
Words nearby penumbral
How to use penumbral in a sentence
The penumbral line is marked from hour to hour on the maps given annually in the American Ephemeris.
I think the intellect, when focussed so as to give definition without penumbral haze, is sure to realise this image at the last.Fragments of science, V. 1-2|John Tyndall
Strange, penumbral, characters roam the boardrooms of banks in the countries in transition.After the Rain|Sam Vaknin
Isabel snuck into the guest bedroom and settled into an overstuffed armchair at a penumbral corner.The Capgras Shift|Sam Vaknin
It may be that all the elements of the penumbral cone intersect the earth.