In my post on Slavic echoes (or the lack of them) in Tolkien’s works, and especially in the comments which it prompted, I talked about the temptation to find such echoes in unlikely places out of mere wishful thinking. But I also acknowledged that Tolkien’s linguistic borrowings were diverse and layered. He liked to imbue words with multiple shades of meaning, or even double-meanings, within and across languages. A classic example of Mordor, which in Sindarin is the “black land”, but which also points to Old English morðor “murder”.
Having thus set the table, let me serve you up a dish of spiders. Specifically, the great poisonous Spiders of Mirkwood. It is pretty well known by now that Bilbo’s taunt, “Attercop! Attercop!”, simply means “poisonous spider” . The compound átor-coppe “spider” is attested in the Old English literature. I do not know of any occurrence of this compound form in Old Norse (one does find köngur-váfa, in which the second element, rather chillingly, means “ghost”), but I’d think it would have been *eitr-koppr. The Old English compound also made its way into Welsh as adargop, eventually shortened to adrop.
Gilliver, et al., think that Tolkien encountered the word while making notes on the 13th-century poem “The Owl and the Nightingale” as an undergraduate. Could be, but I wonder whether he might have seen the poem by Robert Graves, “Attercop: The All-Wise Spider”, published in 1924 . Tolkien used the word “attercops” in early drafts of the poem “Errantry”, probably composed at the beginning of the 1930’s, perhaps even a bit before. (“Attercops” survived into the version published in The Oxford Magazine, 1933, but was not retained in the version printed in The Adventures of Tom Bombadil, 1962.) In his poem, Graves is more complimentary to the reviled creature (“Attercop, whose proud name with hate be spoken”), but the poem, and its use of this archaic word, could have been prominent enough to catch the eye of Tolkien, a young poet himself at the time. Tolkien later described Robert Graves and a lecture he (Graves) gave in 1964: “A remarkable creature, entertaining, likeable, odd, bonnet full of wild bees, half-German, half-Irish, very tall, must have looked like Siegfried/Sigurd in his youth, but an Ass.) It was the most ludicrously bad lecture I have ever heard” . Bees, eh? Well, in Old Swedish, a kopp was a “bee”, and *etter-kopp might have been a good substitute for “wild bee” (or today’s Africanized “killer” bees). Ah, but this is just in fun.
Returning to real etymology, the first element in “attercop” goes back to Old English átor (and variously, áter, áttor, ǽtor, etc.), meaning “poison”; cognate forms in the other Germanic languages include Old Norse eitr, Old High German eitar, Old Saxon êttar, hêttar, and among the modern languages this survives in Swedish etter. In Modern English, the word adder, a kind of poisonous snake, derives from Old English nædre, but it could be that átor “poison” influenced the word.
The second element, cop(pe), is usually said to mean “spider” (it survives in Modern English cobweb), but I think it probably came to refer to the arachnid relatively late, and there is much more to say about its earlier etymology. There are three possibilities: (1) “head”, (2) “cup”, and (3) variously “pock, bag, blister”. But when you boil these down, I think it all comes down to one source: PIE *keup “a hole, a hollow”, which gave IE *kaput “head”. How does a head come from a hollow? Think about it. :)
From PIE *keup / IE *kaput developed such related words as Sanskrit कूप /kūpa/ “a pit, well, hollow, cavity”; Greek κύπελλον “cup, goblet”, from κύπη “a hole, hollow”; and Latin caput “head” and cupa “vat, cask, butt” (if you’re snickering at the latter, it’s the source of Modern English butler). Moving forward into the Middle Ages, we have Old Church Slavonic kupa “cup”, OE copp, cuppe “cup, vessel”, ON koppr “cup, small vessel”, and Middle High German kopf “a drinking vessel”. Ah, but that last word looks familiar, doesn’t it? Modern High German has Kopf for “head”, along with Haupt, phonologically related. Modern Dutch, Danish, and Swedish have kop, kop, and kopp, respectively, for “cup”, and Afrikaans gives kop the additional shades of a hilltop and (informally) common sense (i.e., what’s in your kop “head”).
What about “pock, bag, blister”? Where in the world do those come from? Well, a pock is a small hole, related to the American southern dialectal poke (cf. “a pig in a poke”), which is a bag. These two are clearly related, not by etymology but by sense, to PIE *keup “a hole, hollow”. In addition to the meanings of both “cup” and “head”, Modern Frisian kop also has the sense of “blister, bubble, pock”, and so it’s no great leap to the sting of a poisonous spider. But this leap is not mine; I came across this theory (more tenuous than the others, if you ask me, but still connectable to them) in a 19th-century issue of the Proceedings of the Philological Society of London .
We’ve thus found a kind of double meaning — “head” versus “cup” — is the second element of attercop. Spiders are both “heads of poison” and “cups of poison”, and they may even have “bags of poison” or deliver a “pox of poison”. But I’m not finished yet.
Where do these Attercops live? Mirkwood of course. Again, it is pretty well known that Tolkien took the compound name for his forest from the Old Norse Myrkviðr, and he extrapolated an unattested Old English form, Myrcwudu, for use in his own legendarium . The first element, English mirk, later murk(y), means “dark(ness)” in all the Germanic languages, e.g., ON myrkr, OE mirce, myrce, OS mirki, Modern Norwegian and Swedish mörk, Danish mørk. Even in Tolkien’s own invented languages, we have Queyna morë and Sindarin môr “dark”. This goes back to an Indo-European root *mer meaning “to flicker” (cf. Lithuanian mirgėti “to glimmer”), from which the Primitive Germanic *merkwia “twilight”.
So where’s the double-meaning? Ah, well, recall Tolkien’s interest in Finnish. There, we find the Finnish word myrkky, which is quite close phonologically, but which doesn’t mean “dark” at all; no, it means “poison”, just like the first element of “attercop”! Cognate to these are Estonian mürk, Hungarian mérĕg, and Lappish mir’hku, all meaning “poison”, and all looking like the first element in Mirkwood. Russian моръ “plague, pestilence” may also connected to the idea of poison. Coincidence? It could be, but I tend to doubt it. We know Tolkien studied Finnish (and to some extent modeled his own Quenya on it). The word myrkky doesn’t seem to occur anywhere in the Kalevala; however, we do find the phrase kuolla myrkystä “to die of poison” in Charles Eliot’s Finnish Grammar, the book Tolkien used in his studies of the language .
And I’ve still got one more. Who else have we got in the Mirkwood episode besides the Spiders, Mr. Baggins, and his Sting? Dwarves. How on earth could dwarves and spiders be connected etymologically? It just so happens — and I’ve known this for ages, but have had it up my sleeve awaiting the right opportunity — that dialectal Swedish uses the word dwerg for “spider”; of course, many of you probably know that its primary meaning is “dwarf”. Welsh exhibits the same behavior, where corr is both “dwarf” and “spider”, “the name probably given from the mythical skill of the dwarfs in handicraft” . It’s all about metaphor, and quite possibly Tolkien knew of one or both of these usages.
So, double-meanings, ranging fairly wide, but among languages we know Tolkien studied and with strong ties to the same characters and setting in his first novel. Whether consciously intended or not, such interwoven meanings, like a spider’s web — or better, Ariadne’s thread — they help us to appreciate the ever rewarding complexities of Tolkien’s imagination.
 See, for example: Gilliver, Peter, Jeremy Marshall, and E.S.C. Weiner. The Ring of Words: Tolkien and the Oxford English Dictionary. Oxford: Oxford University Press, 2006, pp. 91–2; and Rateliff, John. The History of The Hobbit, Part One: Mr. Baggins. Boston: Houghton Mifflin, 2007, p. 321n27.
 Graves, Robert. Mock Beggar Hall. London: Hogarth Press, 1924, pp. 14–5.
 Tolkien, J.R.R. The Letters of J.R.R. Tolkien. Boston: Houghton Mifflin, 1981, p. 353 (#267).
 Wedgwood, Hensleigh. “Notices of English Etymology.” Proceedings of the Philological Society of London, Volume II, Number 26 (22 November 1844), p. 6. For the same point again, see also the excellent and thorough, Adams, Ernest. “On the Names of Spiders.” Transactions of the Philological Society. Berlin: A. Asher & Co., 1859: 216–27, p. 217.
 Gilliver, et al., p. 165.
 Eliot, C.N.E. A Finnish Grammar. Oxford: The Clarendon Press, 1890, p. 143.
 Adams, p. 221.