Conrad alerted me to the strikingly discursive OED etymology of the word they list as “grey, gray, a. and n.” After a brief and boring account of its origin (it’s from Old English grǣᵹ, and has only Germanic cognates), they provide this exhaustive inquiry into its alternate spellings:
Each of the current spellings has some analogical support. The only mod.Eng. words repr. OE. words ending in –ǽᵹ are key (which is irrelevant on account of its pronunciation), whey, and clay. If we further take into consideration the words repr. OE. words in –ǽᵹe, viz. blay or bley, fey, wey, we have three (or four) instances of ey and only two (or one) of ay. On the other hand, this advantage in favour of grey is counterbalanced by the facts that clay is the only word of the five which is in very general use, and that grey is phonetically ambiguous, while gray is not. With regard to the question of usage, an inquiry by Dr. Murray in Nov. 1893 elicited a large number of replies, from which it appeared that in Great Britain the form grey is the more frequent in use, notwithstanding the authority of Johnson and later Eng. lexicographers, who have all given the preference to gray. In answer to questions as to their practice, the printers of The Times stated that they always used the form gray; Messrs. Spottiswoode and Messrs. Clowes always used grey; other eminent printing firms had no fixed rule. Many correspondents said that they used the two forms with a difference of meaning or application: the distinction most generally recognized being that grey denotes a more delicate or a lighter tint than gray. Others considered the difference to be that gray is a ‘warmer’ colour, or that it has a mixture of red or brown (cf. also the quot. under 1c below). In the twentieth century, grey has become the established spelling in the U.K., whilst gray is standard in the United States. There seems to be nearly absolute unanimity as to the spelling of ‘The Scots Greys’, ‘a pair of greys’. As the word is both etymologically and phonetically one, it is undesirable to treat its graphic forms as differing in signification.
(I love the Victorian appeal to the printers of The Times, Messrs. Spottiswoode and Messrs. Clowes, and “other eminent printing firms.”) I find it somewhat bizarre that a lot of people tried to differentiate the spellings according to meaning, but on reflection, it’s just one more example of humanity’s insistence on imposing meaning everywhere it turns.
In the entry proper, I found this (presumably long-forgotten) proverb: “the grey mare is the better horse: the wife rules the husband. Hence, in allusion to this proverb, simply the grey mare: the wife who rules her husband.” And I was amused to see, among the DRAFT ADDITIONS FEBRUARY 2004, “(A name for) a member of any of various supposed species of grey-skinned, humanoid, extraterrestrial beings. Usu. in pl.” First two cites:
[1987 Chicago Tribune (Nexis) 22 Mar. 6C, Skeptics who balk at the notion of flying saucers and little gray men are called closed-minded.]
1989 UFO Sept.-Oct. 37/1 The ETs I’ve experienced have exhibited a wide range of forms. I have had no contact with the ‘greys’ (from Zeta Reticulum), and have been told that I will not need to.
“And have been told that I will not need to”: must have been a relief!