I recently encountered a refutation of the idea that a) dinosaur fossils and some sort of fear-of-snakes ancestral memory gave birth to the image of the dragon across a number of cultures and b) that (accordingly from a) and referring more closely to folklore) all cultural dragon-like ideas were related. The serpent-slaying myth may be very old - but it is a very old myth from a distant Indo-European culture, and there is much of the world that is not Indo-European.
Now, we obviously connect the Western dragon of Beowulf (say) with the Chinese dragon - though this is the result of translation. But a fantasy setting that uses the real world or something very close to it might (often does?) throw into the dragon family all sorts of other things. Smaug's cousin is the Hydra; his aunt is Leviathan; he went to school with the Lambton Worm and the Naga. Shadowrun, for one, did this.
But let's step away from that idea for a moment. Let us posit that various types of dragons are not at all closely related: that Nidhogg would take comparison with Tiamat the way you or I might take comparison with a baboon. To illustrate this if we glance at the current Linnean taxonomy for baboons and humans, you have to go from Species past Genus and Family to Infraorder (the Simiiformes) to find them in the same category. There's a very clear distinction between them - aside from all the differences you might already care to name between humans and baboons.
Proposal: in building a fantasy world, you may include dragons or dragon-like things, but you cannot use the word dragon. Now, if you read this blog, I suppose the chances are you already know a dozen alternatives for dragon. Some dragon-like images deviate from the fire-breathing winged Western norm sufficiently to not require adjustment - as the Feathered Serpent or Couatl of Meso-American myth. Deliberately playing up the noble and mammalian qualities of the Chinese dragon or lung could work. But referring to the zmei brings one fairly directly to 'Slavic dragon'.
So....does one have to deliberately reshape the dragon? Referring to 'wyrm' works because of the closeness to worm, but we may want other terms. You could use something like Serpent-Prince or Lizard-King - though the latter brings us too close to the spectre of the tyrannosaur. Giant Snake is good, but leaves out other properties of the dragon. Perhaps kenning is the way to go: Hoardkeeper, Firetongue, Goldtwiner.
Are there any additions you would care to make to this list? How can we avoid using the word dragon?