If you’re a writer of fiction that isn’t set wholly in Earth’s past or present, you’ve more than likely come across a situation requiring a word that simply does not exist. Science fiction has alien or future human technology; fantasy has magic and elves and the like. Sure, English has about a million words (depending on who’s counting) available for you to use, but sometimes that’s just not enough.
We’ve got a few ways we can fill this void. Which one is best depends on a lot of factors. For fantasy and aliens, you might need to come up with a fictional word from a fictional language. (If you do, well, maybe you should look at the Friday posts around here.) Established authors do this all the time, and not only to write epic conlang poetry. Tolkien casually dropped Elvish words like lembas into dialogue. Larry Niven’s Ringworld is constructed around a skeleton of scrith, an alien material stronger than anything humans could dream of making. And those are but two examples among many.
Technically, however, those are loanwords, linguistic borrowings that aren’t necessarily from any real language. For stories revolving around the interactions of disparate cultures, that might be exactly what you need. More human-focused writings, however, might want something else. This is especially true for, e.g., near-future sci-fi, where everything is mostly as it is today, apart from a few oddities. For these, we need to delve into the world of neologisms.
The making of a word
If you look at a dictionary of the English language, it’s obvious that no one sat down and came up with all of those hundreds of thousands of words in isolation. No, there are rules for most of them. Building blocks. Our language has a wide array of prefixes and suffixes, mostly borrowed from Latin and Greek in ages past, that allow us to create new terms with predictable meanings. (Linguists call this agglutination.) For example, we’ve got prefixes like un-, ex-, or over-, and then suffixes such as -ation, -ism, and -ness; Wikipedia, among others, has a whole list you can use.
Many of the new entries in the language—the more “technical” ones, at least—are fashioned by this process of agglutination: Internet, transgender, exoplanet, etc. All you have to do is snap the right pieces together to get the desired meaning, and there you go. In futuristic science fiction revolving around technological advancement, this may be all you really need.
Another option is even simpler: just use an existing word, but in a new context. We’re seeing that one a lot today, with terms like cast or stream or even tweet being reinterpreted to fit our modern world. Here, though, you have to be careful, because even if your characters understand the new meaning you’ve given these words, your readers might not. If you’re going this route, then, be sure to work in an explanation somewhere.
Compounding is another good option. Unlike agglutination, this sticks whole words together into a single, cohesive unit: swordmage, dragonborn. This process, in my opinion, is more suited to fantasy and such; it sounds less “scientific” to my ears. Your mileage may vary, however.
A kind of “opposite” of compounding and agglutination can be made by abbreviation. Different fields use this for jargon nowadays; in sci-fi, especially of the military or paramilitary varieties, this can make the narrator seem to “fit in” better. Shortened words like tac for tactical, vac for vacuum, and mag for magazine are mainly what I’m talking about here. They work best in dialogue, but putting them in narration is fine, as long as you make sure the reader is on board.
Last is the option of pure coinage—making a word from scratch. Unless you really know what you’re doing (or you’re not opposed to some serious linguistic construction), you might want to steer clear of this one. Here, you’re making a word that doesn’t actually exist, in whole or in part, and that’s a lot harder than you might think. When it’s not intended to be an “alien” word, whatever that may mean for your story, it’s actually quite difficult to come up with something that doesn’t sound corny and forced. For this one, I can’t really give much advice beyond “Play it by ear.”
However you choose to do it, adding new words (or new meanings for old words) really can help set the “otherness” of a world. An unfamiliar or nonexistent term is a sure sign that we’re not dealing with the ordinary anymore, whether it’s in there because you’re talking about aliens, elves, assault weapons, or the mysteries of the universe. (On a personal note, my forthcoming novel Nocturne uses neologisms to describe its magic; they’re all compounds.) Now, if you want to make a whole language, then check the “conlang” section of the site. And if you’re simply looking for technobabble that would make a Trekkie proud, well, that’s a different post. Maybe I’ll write it soon.