1650s, "pale, wan," from Latin luridus "pale yellow, ghastly, the color of bruises," a word of uncertain origin and etymology, perhaps cognate with Greek khloros "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.