Engines, Motors, and Reactions
I described on the reaction engine's talk page how we need to rework our terminology because Wikipedia defines jet engines as a kind of reaction engine. KSP doesn't even use the term “reaction engine” anywhere, but it's a catch for rocket engines, SRBs, jet engines, RCS, and really anything that burns chemical fuel.
That led to questions about this article.
Currently, the Engine article lists rover wheels as a type of engine. It's technically correct, but awkward; KSP doesn't list them in the "Engines" parts tab. They're non-reaction engine "engines", but by the same logic the torque in SAS modules and command pods is an engine; you can flip-walk things across terrain!
I don't know what the best approach to this one is. There's a clear in-game meaning to "Engine" as things under the "Engine" parts tab". But I've seen a phantom force driven water speeder by Danny4682, infini-gliders, and a flying contraption made of symmetrically placed landing legs pushing against a slightly-too-close metal panel.