The "About Us" page for the new search engine Cuil says that
Cuil is an old Irish word for knowledge. For knowledge, ask Cuil.
There has been considerable discussion at the Wikipedia discussion page for Cuil about whether this is really true.
I certainly don't know the word and it's not in any dictionary I have easily to hand.
There are two words `cuil' that I know. One means `enmity' or `bad attitude' or `resentment', as in
|"He's angry with me/resents me/has it in for me."|
The other means `fly'.
But maybe it's some Old or Middle Irish word — I'd have to check the Royal Irish Academy dictionary for that.
Commenter Nick Z did check the Royal Irish Academy dictionary, and wrote that
According to the "Dictionary of the Irish Language. Based Mainly on Old and Middle Irish Materials" (Dublin: Royal Irish Academy), in Old and Middle Irish there was a word coll "hazel-tree; 3rd letter of the alphabet". I don't know if this would become cuil(l) in Modern Irish; it appears as cuill only in the genitive singular in O and MIr (as expected for an o-stem noun).
There is no word cuill.
I couldn't find any words of a similar shape meaning "knowledge". cuil means "fly" (the insect). cuil, with a long -u-, means "corner, recess". cul, with a long -u-, means "back, rear". col means "wrong, infringement, violation; incest".
I also searched English meanings at eDIL (http://www.dil.ie/search-all.asp) for "knowledge" without finding anything likely.
At least in Old and Middle Irish, there doesn't seem to have been a word cuil(l) "knowledge".
(a) Of persons sense, intelligence, mind [...] More particularly wisdom, good sense, skill [...]
(b) Of bodily senses [...]
(c) In a variety of more general applications intention, cause, reason, idea [..]
(d) Of words, texts, etc. signification, meaning [..] Of grammatical forms force, function, meaning [...]
Whether there's a plausible way to get from cíall to "cuil" (under whatever spelling) isn't clear to me.
The Cuil FAQ offers a more detailed version of the story, in answer to the question "What does the name Cuil mean?":
Tom Costello, our founder and CEO, comes from Ireland, a country with a rich mythology around the quest for wisdom. Cuil is the Gaelic word for both knowledge and hazel, and features prominently in ancient legend. One famous story tells of a salmon that ate nine hazelnuts that had fallen into the Fountain of Wisdom and thereby gained all the knowledge in the world. Whoever ate the salmon would acquire this knowledge.
A famous poet fished for many years on the River Boyne hoping to catch the Salmon of Knowledge. When he finally caught it, he gave it to his young apprentice Finn McCuil to prepare, warning him not to eat any. As Finn cooked the salmon he burnt his thumb and instinctively sucked it to ease the pain. And so it was Finn and not the poet who gained all the wisdom of the world. Finn went on to become one of the great heroes of Irish folklore. Any time he needed to know the answer to a question, he sucked his thumb.
As a child Tom poached salmon from the same spot on the Boyne where it is said the Salmon of Knowledge was caught.
The Wikipedia entry suggests that Finn's patronymic should be spelled "mac Cumhaill", where (as I understand it) "Cumhaill" is the genitive case of the name of Finn's father Cumhall. The etymology of "Cumhall" is disputed, but seems not to have anything to do with knowledge, hazelnuts, salmon or words spelled "cuil".
I'll await further information on the subject from experts in Old Irish, which I definitely am not. But for now, I can report that under a different spelling, Finn MacCool plays a relevant role in one of my favorite books, Flann O'Brien's At Swim-Two-Birds.
At the start of the book, Finn appears in mental counterpoint to a breakfast discussion with the author's uncle, mixed with a diverse collection of other imagined individuals in a way that seems eerily appropriate for the possible namesake of a modern search engine:
Having placed in my mouth sufficient bread for three minutes' chewing, I withdrew my powers of sensual perception and retired into the privacy of my mind, my eyes and face assuming a vacant and preoccupied expression. I reflected on the subject of my spare-time literary activities. One beginning and one ending for a book was a thing I did not agree with. A good book may have three openings entirely dissimilar and inter-related only in the prescience of the author, or for that matter one hundred times as many endings.
Examples of three separate openings–the first: The Pooka MacPhellimey, a member of the devil class, sat in his hut in the middle of a firwood meditating on the nature of the numerals and segregating in his mind the odd ones from the even. He was seated at his diptych or ancient two-leaved hinged writing table with inner sides waxed. His rough long-nailed fingers toyed with a snuff-box of perfect rotundity and through a gap in his teeth he whistled a civil cavatina. He was a courtly man and received honour by reason of the generous treatment he gave his wife, one of the Corrigans of Carlow.
The second opening: There was nothing unusual in the appearance of Mr. John Furriskey but actually he had one distinction that is rarely encountered–he was born at the age of twenty-five and entered the world with a memory but without a personal experience to account for it. His teeth were well-formed but stained by tobacco, with two molars filled and a cavity threatening in the left canine. His knowledge of physics was moderate and extended to Boyle's Law and the Parallelogram of Forces.
The third opening: Finn MacCool was a legendary hero of old Ireland. Though not mentally robust, he was a man of superb physique and development. Each of his thighs was as thick as a horse's belly, narrowing to a calf as thick as the belly of a foal. Three fifties of fosterlings could engage with handball against the wideness of his backside, which was large enough to halt the march of men through a mountain-pass.
I hurt a tooth in the corner of my jaw with a lump of the crust I was chewing. This recalled me to the perception of my surroundings.
It is a great pity, observed my uncle, that you don't apply yourself more to your studies. The dear knows your father worked hard enough for the money he is laying out on your education. Tell me this, do you ever open a book at all?
A bit later, the mock-heroic explanations continue, including "the attributes that are to Finn's people". Here's a small sample:
Till a man has accomplished twelve books of poetry, the same is not taken for want of poetry but is forced away. No man is taken till a black hole is hollowed in the world to the depth of his two oxters and he put into it to gaze from it with his lonely head and nothing to him but his shield and a stick of hazel. Then must nine warriors fly their spears at him, one with the other and together. If he be spear-holed past his shield, he is not taken for want of shield-skill. [...] Neck-high sticks he must pass by vaulting, knee-high sticks by stooping. With the eyelids to him stitched to the fringe of his eye-bags, he must be run by Finn's people through the bogs and the marsh-swamps of Erin with two odorous prickle-backed hogs ham-tied and asleep in the seat of his hempen drawers. If he sink beneath a peat-swamp or lose a hog, he is not accepted of Finn's people. For five days he must sit on the brow of a cold hill with twelve-pointed stag-antlers hidden in his seat, without food or music or chessmen. If he cry out or eat grass-stalks or desist from the constant recital of sweet poetry and melodious Irish, he is not taken but is wounded. When pursued by a host, he must stick a spear in the world and hide behind it and vanish in its narrow shelter or he is not taken for want of sorcery. [...] One hundred head of cattle he must accomodate with wisdom about his person when walking all Erin, the half about his armpits and the half about his trews, his mouth never halting from the discoursing of sweet poetry. One thousand rams he must sequester about his trunks with no offence to the men of Erin, or he is unknown to Finn. He must swiftly milk a fat cow and carry milk-pail and cow for twenty years in the seat of his drawers. [...] Unless he accomplishes these feats he is not wanted of Finn. But if he do them all and be skilful, he is of Finn's people.
Heroic feats of etymology are not mentioned, but perhaps they should have been.