There's recently been a change to the naming disambiguation guideline. http://en.wikipedia.org/wiki/Wikipedia:Naming_conflict#Common_subsets_versu… I'm interested in whether that is considered a good idea or not. For example the term 'internal combustion engine' usually refers to piston engines and wankel engines, but the term technically actually covers gas turbines and jet engines as well, in a less common sense. This is actually the way the Encyclopedia Britannica defines the term, it defines it in the most general sense. If you try to define the everyday sense you end up with an arbitrary definition that is difficult to defend, it's this or that only. Presumably that's why the EB does it the general way. Another example is jet engine, again, it normally covers turbojets and turbofans, but also ramjets, and in the most general (less common sense) it covers rockets and water jet powered boats. That's the way the jet engine article currently goes. The term 'aircraft engine' very often refers to, in aviation usage, just piston engines and Wankel engines used for aircraft, but not to jet engines, however it's easy to find jet engine manufacturers that refer to their jet engines as 'aircraft engines' as well, and the term would lead you to expect it to be more general than just piston engines. The same discussion has in the last two weeks or so recently cropped up in 'glider'. A lot of people use the term to refer to what can be termed sailplanes, and some don't even really consider, for example, 'hang gliders' to be gliders. I agree that people will usually imagine a sailplane when they are asked what a glider is, but I find that they will also usually agree that other things are gliders also. I'm not sure there's a right or a wrong exactly, but the wikipedia is probably a general publication and therefore, it seems to me, gets forced in a lot of cases to use general terms, (and this is the catch) even if they're somewhat less common, because the general term is synonymous with the specific term but a superset and usually easier to define. I'm just wondering what people here think about this issue in general and the ongoing 'glider' one in particular. Is 'glider' more or less anything/an aircraft that glides, or is it specifically a (for want of a better name) a sailplane. (FWIW if you want to see how 'glider' used to be see: http://en.wikipedia.org/w/index.php?title=Unpowered_aircraft&oldid=2567… I'm not convinced I understand what that version is doing there specifically, but that's where it currently is.) -- -Ian Woollard We live in an imperfectly imperfect world. Life in a perfectly imperfect world would be very much better.