penumbraladj.
/pᵻˈnʌmbr(ə)l/, /pɛˈnʌmbr(ə)l/, U.S. /pəˈnəmbr(ə)l/ 1. Astronomy. Of or relating to the penumbra of the shadow of the moon or earth during an eclipse, or the penumbra of a sunspot. penumbral eclipse n. an eclipse in which only the penumbra is cast on the earth or moon; a partial eclipse.
ΘΚΠ
the world > matter > light > darkness or absence of light > intercepting or cutting off of light > [adjective] > casting a shadow > of or relating to or resembling a shadow > partial
penumbral1737
penumbrous1875
1737 London Mag. Jan. 34/1 At length the Center of the Penumbral Shadow arrives in Ireland.
1769 Philos. Trans. 1768 (Royal Soc.) 58 331 It was remarkably distinct from the penumbral shade.
1822 T. Webster Imison's Elem. Sci. & Art (new ed.) I. 443 Places which fall within this penumbral cone, and are out of the dense shadow.
1882 Cent. Mag. Apr. 818 A faint eclipse, penumbral, gone full soon, Yet marking on the planet's smoky ring A silhouette as of a living thing.
1906 Westm. Gaz. 23 Dec. 5/1 The complement of the penumbral eclipse of the moon visible here a fortnight ago takes place to-day as an annular eclipse of the sun.
1941 Sci. Monthly Apr. 322/1 Studies..of the spots themselves, particularly of the penumbral filaments, should give additional information about sun-spot circulation.
1994 Times 31 Oct. 20/4 The eclipse of the Moon on the 18th will be penumbral, with the Moon not entering the Earth's central shadow.
2. In extended use: shaded, in semi-darkness; shadowy, indistinct; peripheral.
ΘΚΠ
the mind > mental capacity > belief > uncertainty, doubt, hesitation > insecure knowledge, uncertainty > [adjective] > obscure, vague
cloudyc1400
indeterminatec1400
diffuse1430
diffused?1456
obscure?a1475
infinite1520
ambiguous1529
indistincta1530
nubilous1533
dark1557
undetermined1588
undefinite1589
undeterminate1603
indetermined1611
undefined1611
suspense1624
umbrageous1635
clouded1641
undeterminated1641
fuliginous1646
implicit1660
vague1690
diffusive1709
nubilose1730
foggy1737
unliquidated1780
hazy1781
indecisive1815
nebulous1817
penumbral1819
aoristic1846
scumbled1868
nubiform1873
out-of-focus1891
fuzzy1937
soft focus1938
1819 Philos. Trans. (Royal Soc.) 109 290 The penumbral boundary [of oil-saturated tabasheer] which might be supposed to separate the opaque from the transparent part.
1856 E. K. Kane Arctic Explor. II. i. 14 We are looking forward to this more penumbral darkness as an era.
a1922 T. S. Eliot Waste Land Drafts (1971) 37 Within this penumbral consciousness.
1965 Mod. Law Rev. 28 510 The Appeal courts..are primarily concerned with penumbral issues.
2000 Times 30 Aug. ii. 14/2 The guests were forced to walk to the dinner party since all cabs were marooned in the penumbral streets.
This entry has been updated (OED Third Edition, September 2005; most recently modified version published online March 2022).
<
adj.1737