Some words look like they were invented just to poke at your eye, perhaps to make some point. This one has that kind of angle – I mean, in English, cn is just not a natural onset. We might accept kn, pronounced /n/, but cn makes me think of that uncomfortable sticky state your soft palate gets in when you’re fighting a cold. And in case you miss it the first time, it’s there a second time in this word – and while you can make the c silent the first time, it’s across a syllable boundary the second, so you have a real /kn/ (without that /k/ it would all stay on the tip of your tongue – inasmuch as this word is likely to be on the tip of your tongue).
But what is this word? What does it mean? Where does it come from? Well, forgive me for not getting right to the point, but I want to say first that it has nothing to do with cinch or with nicky nicky nine doors or with kinnikinnick, which is another name (a rather likeable one) for bearberry. It does have something to do with blessed thistle and safflower, but only because Cnicus is (or rather was, before it was reclassified) the genus of the blessed thistle and is the Latin for “safflower” (taken from a Greek word for a thistle – it’s because it came to us through Latin that it’s cn rather than kn; Latin doesn’t use k, whereas in the original Greek the /k/ was represented by kappa, κ, which is normally transliterated to English as k, reasonably enough).
The node in cnicnode, by the way, is from Latin nodus, “knot” or “node”. So we have something that seems like a thistle node. But actually the word was invented by the noted 19th-century British Mathematician Arthur Cayley. (A nice name, Cayley, no? Makes me think of inverted cones, sort of, with those two y‘s, and perhaps part of the base of a cone with the C.) And what is it? Well, not to put too fine a point on it, it’s a point where tangents form a cone of the second order – more to the point, it’s the sharp end of a cone. I know not whether it is coincidence that cnicnode anagrams to conic end.
This word doesn’t really look pointy, does it? To my eyes it’s more reminiscent of a chain. It even looks sort of glued together from opposing bits. You see the cn stuck together (perhaps with cyanoacrylate) and wonder if it’s in code, or is perhaps some nonce word. Or at least if someone left out the o and the space in conic node. Well, whatever it is, once you know it’s math you know it’s something you’ll have to sharpen your pencil for.