Yes, it is very true that we collectors do not have a standard dictionary of terms. Not even in a single language! Things become more confused with foreign languages because translations are sometimes difficult.
One problem is non-standard items are often not documented. Is it a "trial", is it a "sample", is it "commercial, but unofficially used", when does something become "standard, but not official"???? Many questions, no easy answers.
A good example of this...
A friend of mine in the Belgian Para/Commandos requested US Woodland uniforms from me. The reason? Belgian issued uniforms are very expensive if damaged and they must always maintain a certain number of uniforms. Therefore, the Belgian soldiers do not like using them for dirty/hazardous work. So I sent a couple HUNDRED US Woodland jackets and trousers to Belgium. If someone visited the base while they were doing dirty/hazardous work that visitor might conclude "the Belgians wear US Woodland uniforms!". This is false. The person may instead think "the Belgians unofficially use US Woodland uniforms!". This is true for that one unit, but it isn't true for the Belgian Para/Commandos or the entire Belgian Army.
So I am possibly responsible for causing a collector 10 years from now to be very, very confused when he finds a US Woodland uniform in a Belgian warehouse