Choose your words carefully
There are reasons why many fantasy stories take place in an ersatz Merrie Englande composed of equal parts Robin Hood, King Arthur, Prtince Valiant and cheese. Of course, one reason is imaginative bankruptcy, but there's more to it than that. The more you sing a tune the audience has heard before, the more they can fill in the words for themselves. Hence the standard fantasy landscape of castles, forests, wolves, elves, wizards, vampires and all that jazz (1).
If your setting is less stereotypical, your path less trodden, then you have a cognitive gap to make up. If your world deviates from the world, then in those places where fiction and fact fail to meet, you can trip yourself up no end. Mind the Gap.
Example the first: zoology.
The insect kinden live in a world devoid of land vertebrates save for a very few domesticated exceptions that humanity was able to save from the chitinous purge. All well and good. Only when you come to the nuts and bolts of it, though, do you realise just how much of our language is built from animal metaphors: take the bull by the horns, hawks and doves, the cat that got the cream, fox amongst the pigeons, a tiger by the tail and so on and so forth. Frequently the animal imagery is second nature, the natural cliché to slip in, to save a hundred words.
But: no bulls (2), hawks, doves, cats, foxes, pigeons, tigers, mice, elephants, dinosaurs, duck-billed platypes or any of the rest of the crowd. The insects got 'em, every last one (3).
The metaphors and similes are actually relatively easily avoidable (4). However, there is a deeper level where the bestial has become the etymological: hounding your footsteps, dogged expressions, being his catspaw, hawk-featured (5). Worse, there are some anomalies that are basically unavoidable, because the invertebrate is named for the vertebrate: how can I have dragonflies, stag beetles or skunk-nosed woolla-woolla weevils (6) when I have no dragons (8), stags or skunks?
Two choices face the desperate writer at this juncture. Firstly he descends into gibberish and calls it either
(a) A Schwoedge, which is just meaningless.
(b) A Razorwing, which is just gratuitous
© An Arcturian Mega-Fly, which is just borrowing from Douglas Adams.
Secondly, he calls the bastard a dragonfly and uses the linguistics defence. The linguistics defence runs as follows: these people are not speaking English. They are speaking some mad language of their own, that your humble raconteur has translated into something you, the eager reader, can understand. Whilst those fictional people will call our dragonfly something like (a), (b) or, admittedly less likely, © above, I decipher their nomenclature to identify the thing as what you, in your innocence, know as a dragonfly. Hey presto, dragonflies without dragons.
Example the second: divinity
So, you have a world without religions: no concept of god, hell or the devil has come to trouble them. The missionaries never arrived (9) and the natives live in a state of grace.
This is a lot more difficult than the animal issue, because our language is riddled with religious terms, and when we get het up about things, as characters in fantasy novels often are, such oaths tend to rise to the surface. I won't go into the same level of detail, but suffice to say that I had a hell of a time hunting down the damned things, and lord knows I surely missed a few. Of course, although there are no religions, some of the Inapt kinden have a spiritual framework, so when a Mantis-kinden talks of being damned, for example, that is in keeping. It's a moveable last supper, so to speak.
Example the third: modernity
David Gemmell once said to me (10) that he used the phrase "to fire" of bows and arrows in one of his books, and was challenged about it (11), and in his defence was forced to invent a lost mechanistic past to account for one of his characters using the phrase. Of course, Gemmell's work is pulp-style fantasy, and lost races and ancient technologies are very much in keeping, but it might have been simply just to yank out the chap's beard (12) in a fit of piqué and leave the backstory where it was. However, the point stuck in my mind, and — by Toutas! — I have done my bloody level best to ensure that nobody fires a bow, or a crossbow, or a ballista. Nobody even fires a nailbow, which is a kind of rather primitive gunpowder repeater, because they're very new and unreliable and there hasn't been the opportunity for the phrase "give fire" (from musket drill originall I think) to transform into the everyday very "to fire a weapon". Am I a perfectionist? Count how many of the sods I've missed and then ask me.
(1) Or at least Hawkwind-ish heavy metal.
(2) I confess to the phrase "take the beetle by the horns" appearing in book 2 somewhere, unless they edit it out.
(3) There's a tragic story in that: the last duck-billed platypus, growling and snarling, backed into a corner by a weta the size of your head.
(4) by saying this I'm guaranteeing that one has slipped through, and will be brought to my attention at every available opportunity.
(5) Although no problem with beetle brows or the bee's knees.
(6) I made that one up (7)
(7) At least I think I made that one up. Given the million or so insect species kicking about, maybe I didn't.
(8) Absolutely no dragons. Also no elves or dwarves. Some wizards, however. Perhaps fantasy books should come with some sort of dragon-content warning on the back cover?
(9) and/or were eaten by enormous insects.
(10) in all honesty he also said it to the large crowd of people I was hidden amongst.
(11) almost certainly by a civil war re-enactor, frankly.
(12) You know the objector had a beard, you just do.