Setting Terminology in Stories

[Tsundere Lightning]

Whenever possible, adapt an existing English word to create in-universe jargon, or use compound words. Then introduce them in a context that gives you SOME, but not all, of the intended meaning and fill it out as you go.

For example: "They set a slamhound on him, slotting it to the precise smell of his sweat before launching it into the city." Great! What's a slamhound? I'm not sure, but the context and the English name make it seem like a robotic tracker of some kind that does NASTY things to whatever it seeks.

Or for another example: the Dive in my Bliss Stage VN, which refers to the act of entering a dream in order to do battle with psychic monsters. I picked this term because implies a whole bunch of other useful metaphors: Going Under, Surfacing (waking up), (Dream) Depth, being Submerged. Likewise, the terms for the tech they use for this (which I didn't make up; it's from the source material) all has a maternal metaphor: the hangar bay is the Creche, while the psychic weapon control pod is a Cradle.

I don't like making up strange collections of syllables nearly as much, although it can work well if you're making up a whole language to go with it. This is the route that Tolkien took with the Sindarin and Quenya dialects of his Elves, as did Star Trek with the Klingon language and Disney with Atlantean. If you're interested in doing this, I recommend taking a look at The Language Contruction Kit, a webpage of constructed language resources made by a linguist for fantasy and sci-fi writing laymen.