It has come to my attention that many people don’t know shit about dragons, so let me help you out.
Dragon: 4 legs, 2 wings.
Also Dragon: 2 legs, 2 wings
Also Dragon: 4 legs, flightless
Also Dragon: Limbless
Also Dragon: 4 legs, can fly
Also Dragon: 0 legs, 2 wings
Also Dragon: 0 legs, 0 wings
“But wait!” You, my hypothetical Strawman wail. “I thought that was a wyvern/wyrm/drake! Does this mean tumblr and pop culture has been lying to me this entire time?”
Not exactly, but it has been getting things not 100% right either.
Dragon an Umbrella Term, meaning there are a lot of creatures that fall under that heading. Something with two wings and two legs is a Wyvern, but that doesn’t mean it has stopped being a dragon.
So why the confusion? Part of it has to do with the fact fiction is free to define these terms how they want. In the context of D&D a Wyvern isn’t a dragon, but D&D is borrowing these creatures from myth, and doesn’t make the rules when it comes to interpreting said myths.
Another part of the issue is that Dragon, referring to the subtype with four legs and two wings, has no other name. It shares the name of the group. An example I use to demonstrate a similar case is Tigers vs Cats. Tigers are a species of cat, no one will deny this. Tigers are not, however House Cats. See what I mean? Wyverns are Dragons (The Group) but they are not Dragons (the subtype with four legs).
Additionally, because I have seen this a bit, unless you are using Wyrm as a synonym for Dragon: The Umbrella Term, do not call East Asian dragons Wyrms. The term Wyrm is heavily steeped in European tradition, while East Asian dragons are heavily steeped in their own. At best it’s ignorant, at worst it’s culturally insensitive. If you want a name for East Asian dragons, use one of the native terms. Which, now that I’ve confused you with the pictures, here are some terms.
Dragon- Umbrella Term for entire Group.
Dragon-Four legs, wings.
Wyvern- Dragon with two legs, wings.
Drake-Wingless, flightless dragon. Alternatively, synonym for Dragon.
Wyrm-Limbless dragon. Alternatively, archaic word for any dragon.
Long/Lung- Chinese Dragon.
Ryu/Tatsu-Japanese Dragon.
Yong/Ryong-Korean Dragon.
Rong-Vietnamese Dragon.
Naga-Indian Serpent/Cobra Dragons.
Amphiptere-Dragon with wings, no legs.
Linnorm-Dragon with two legs, no wings. Alternatively, Scandinavian term for dragon.
Monsters' Queen 