Not a word is a phrase the volunteer grammar militia like to deploy as if it’s a tactical warhead, a megaton-level delivery of dismissal and shame meant to obliterate whatever invention or mutation is too recent to have been granted what they imagine is legitimacy by appearing in The Dictionary. It’s pretty much a paper tiger, of course, because “not a word” is not an argument, and that’s not what the dictionary is for, but at least when you see it you’re getting fair warning of exactly the kind of insufferable fusspot you’re dealing with.
Meanwhile, for most of us, a “word” is a collection of letters with a recognizable meaning, even if its usage is disreputable or in an informal register. But once in a while, the odd corners and alleys of culture give us an interesting edge case. Take, for example, the wordlike phoneme string fnord, which I’m guessing you likely haven’t stumbled across unless your social or aesthetic pursuits have brought you into the circle of the Discordians.
Discordianism is fascinating all by itself: a phemonenon unique in religious history for its commitment to being both a satire of religion and a practiceable faith in equal measure. That should give you an idea of the territory we’re entering here; as a Discordian of my acquaintance once said, “Nothing a Discordian tells you is either entirely serious or entirely in jest,” and that’s a pretty good rundown of the least you need to know when looking into the fnord question.
“Fnord” is a term without a definition (though it does have a Wikipedia entry) used by Discordians as a shorthand for Erisian weirdness, a marker of irony, and a signal of in-group mutual understanding among the initiated. It’s not quite an interjection, but it serves the function of a wink or a sly aside, like a more abstracted LOL for absurdists and anarchists. It’s a “word” invented to have no direct referent, indeed to resist all attempts at being defined; all connotation and no denotation. And in the circles where it’s used, it’s survived for half a century now, which is pretty impressive staying power for something with a meaning intended to stand as a perpetual question mark.
(Now, I can well imagine a Discordian saying that of course fnord has a definition, it’s just that the un-Illuminated are unable to grasp it. It doesn’t take long among Discordians to understand that this is part of the game. The brilliance of fnord is that it’s a mystery disguising itself as a secret, and the joke’s on anyone who can’t tell the difference between the two.)
Douglas Hofstadter, in his essay “Stuff and Nonsense” in Metamagical Themas (a work I regrettably don’t have in front of me, so I’m writing from memory here), wrote about the compelling quality of nonsense – in verse in particular, but other media as well – to suggest that there’s some key piece of information the reader is missing that would make everything clear if only it were revealed. Invented words can be perfectly compact meaning-delivery units when they’re made up of the intuitively right parts; they can also be distillations of that maddening feeling that well-crafted nonsense has to hover just at the edge of meaning without ever coming into view. And some of them slide back and forth across the slippery border between meaning and meaninglessness in interesting ways. I suppose lots of people in the language fields find contemplating that ambiguous space disconcerting, but I’m fascinated by it, and if you are too, you should come sit next to me. Hail Eris! Fnord!