1650s, "pale, wan," from Latin luridus "pale yellow, ghastly, the color of bruises," a word of uncertain origin and etymology, perhaps cognate with Greek khlōros "pale green, greenish-yellow" (see Chloe), or connected to Latin lividus (see livid).
It has more to do with the interplay of light and darkness than it does with color. It suggests a combination of light and gloom; "Said, e.g. of the sickly pallor of the skin in disease, or of the aspect of things when the sky is overcast" [OED]; "having the character of a light which does not show the colors of objects" [Century Dictionary]. Meaning "glowing in the darkness" is from 1727 ("of the color or appearance of dull smoky flames" - Century Dictionary]. In scientific use (1767) "of a dingy brown or yellowish-brown color" [OED]. The figurative sense of "sensational" is first attested 1850, via the notion of "ominous" (if from the flames sense) or "ghastly" (if from the older sense). Related: Luridly.
"hideous, ghastly, weird," c. 1500, of uncertain origin; apparently somehow from elf (compare Scottish variant elphrish), an explanation OED finds "suitable;" Watkins connects its elements with Old English el- "else, otherwise" (from PIE root *al- "beyond") + rice "realm" (from PIE root *reg- "move in a straight line," with derivatives meaning "to direct in a straight line," thus "to lead, rule").
mid-15c., "hermit (especially those of the Eastern deserts in the two centuries after c. 300 C.E.), recluse, one who withdraws from the world for religious reasons," from Medieval Latin anchorita, Late Latin anchoreta, from Greek anakhoretes, literally "one who has retired," agent noun from anakhorein "to retreat, go back, retire (from battle, the world, etc.)," from ana "back" (see ana-) + khorein "withdraw, give place," from khoros "place, space, free space, room," from PIE root *ghē- "to release, let go; be released." Replaced Old English ancer, from Late Latin anchoreta. Related: Anchoritic.
There is, perhaps, no phase in the moral history of mankind of a deeper or more painful interest than this ascetic epidemic. A hideous, sordid, and emaciated maniac, without knowledge, without patriotism, without natural affection, passing his life in a long routine of useless and atrocious self-torture, and quailing before the ghastly phantoms of his delirious brain, had become the ideal of the nations which had known the writings of Plato and Cicero, and the lives of Socrates and Cato. [Lecky, "History of European Mortals"]