What would SF be without weird words to boggle hapless readers? Some authors invent them shamelessly, like A.E. van Vogt with "adeledicnander". This is a future superscience based on the psychology of electrons: "He's been trying to tell me that electrons think ..." "Not think; they don't think. But they have a psychology."
It's more fun when unlikely words have some link with English. One trick is to imagine them evolving with time, like the mysterious chemical "agenothree" in Anne McCaffrey's Dragonflight, which not only dissolves things but is a fertiliser when diluted. Aha! It's a distortion of HNO3, nitric acid. McCaffrey forgot this in a later book, where agenothree became fuel for flamethrowers.
My favourite outrageous use of this gimmick is in Robert Lowndes's now forgotten Believer's World. Three almost identical planets, Speewry, Ghrekh and Pittam, are supposedly named for three different prophets who wrote their holy scriptures – that is, science textbooks. The shaggy-dog revelation is that it's the same textbook in three kinds of shorthand: Speedwriting, Gregg and Pitman. Ouch.
Anagrams sometimes lurk in names. Ursula Le Guin had no idea, when coining the word "ansible" for faster-than-light radio, that evil minds would rearrange it into "lesbian". James Branch Cabell's fantasies are full of deliberate anagrams like the placename Mispec Moor ("compromise"), or dubious gods called Sesphra and Vel-Tyno: "phrases" and "novelty". The anagrammatic secret of J.K. Rowling's character Tom Riddle requires you to remember his middle name, Marvolo. In one Robert Heinlein novel, planetary explorers are warned against "stobor", which to the surprise of anagram-minded readers turn out not to be robots.
Other writers prefer real but obscure words. Jack Vance has horrid maneating monsters appropriately called deodands, old legalese for a chattel (a horse, say) which has caused a human death and is forfeit to the Crown. John Clute's novel Appleseed uses a terrifying range of English, from "kenosis" and "pleroma" to "pong" and "spam". His Author's Note helpfully defines two difficult words – "azulejaria", "mappemonde" – while leaving you to struggle with the jawbreakers that Clute expects you to know.
Kurt Vonnegut mocked SF jargon in The Sirens of Titan with "chrono-synclastic infundibulum", unhelpfully defined as a time funnel with a particular curvature. "If you don't know what a funnel is, get Mommy to show you one." But then he shows you what it does.
The SF master of arcane words is Gene Wolfe, whose Book of the New Sun is full of far-future weaponry made to seem both exotic and familiar by using historical names. Arquebuses, fusils and jezails are ancient firearms (Dr Watson's wandering war wound in the Sherlock Holmes stories was from a jezail bullet), but in Wolfe's saga they're advanced energy guns.
Any fool can swot up impenetrable jargon. Wolfe has a knack of using words that feel right, while making the meaning clear from context. You may not know that a chiliarch is a commander of 1,000 men, but from the text he's clearly a high-ranking soldier. Wolfe himself cagily discusses some of his arcane words in The Castle of the Otter – the title under which his The Citadel of the Autarch was wrongly announced by one SF newsletter. The author liked this so much that he used it for another book.
China Miéville likewise has great fun with names in The Scar, which alludes to a million nautical stories from Moby Dick onward. There's a hunt for a gigantic sea monster called an avanc, perhaps the terrible river-dwelling Afanc of Welsh folklore. (Which gets a bit part in Susan Cooper's fantasy Silver on the Tree, and which in the standard Welsh reference Y Geiriadur Mawr, the Big Dictionary, is bafflingly translated as "beaver".) The avanc project boss is a chap called Tintinnabulum. Aha – the Bellman from Lewis Carroll's The Hunting of the Snark!
So my review called the quest a "snark hunt", and Miéville gleefully pointed out that he'd actually included Carroll's entire crazy crew: Baker, Banker, Barrister, Beaver, Bellman, Billiard-Marker, Bonnet-Maker, Boots, Broker and Butcher, all transposed into other languages. Their ship is the Castor, Latin for beaver ...
I'm sworn to silence about the most awful joke in The Scar, but watch out for what seems to be the kind of hotly pursued plot device that Hitchcock called a MacGuffin – and try not to groan when at last the author names it.
Finally, a really useful word, revealed by L. Frank Baum in his Oz books, which enables you to transform yourself into any shape if pronounced correctly. The magic word is ... "pyrzqxgl".
David Langford's novel The Leaky Establishment has a hero named Tappen. Do not look this up in the dictionary.