penumbra

1 partial darkness due to the obstruction of light rays the lunar eclipse began with a subtle darkening of the lunar surface as it passed within the Earth's penumbra Synonyms dusk, shade, shadiness, shadow, umbraRelated Words blackness, dimness, duskiness, gloom, gloominess, murkiness, obscurity, semidarkness, somberness; cloudinessNear Antonyms brightness, brilliance, effulgence, illumination, incandescence, light, lightness, lucidity, lucidness, luminance, luminosity, luminousness, radiance, radiancy

2 something that covers or conceals like a piece of cloth a penumbra of despair fell over the doomed city Synonyms blanket, cope, cover, covering, coverture, cover-up, curtain, hood, mantle, mask, pall, cloak, robe, shroud, veil, wrapsRelated Words blind, concealer, screen, shield; fig leaf, Potemkin village, Trojan horse; camouflage, disguise, facade (also façade), face, mask, veneer; gloss, varnish