Sphyre said:
What you said would be correct, if the speaker was attempting to deceive or confuse. But, logically, what good would that be if they were intending on trying to confuse, so we can tell that the speaker in this case is not at fault, because their intention is not to deceive or confuse (due to the premise that they intend on making easy to use rules).
There's another possibility, however, which is that the speaker is trying to communicate but doing a bad job of it. In which case it is still the speaker's fault that communication fails.
Sphyre said:
If, though, in your example, you use word X, and people say "What? Y doesn't make sense." You should be prepared to inform the listener of meaning Y as well, since it is the lesser used meaning of Word X.
That's all very well if you are in fact communicating two ways--though it's still very bad form to use a lot of terms that you know will require explanation. You shouldn't have to issue your listeners a dictionary to understand what you're saying, nor should you be constantly stopping to explain your terms. Use language appropriate to your audience.
However, a written book, like the D&D rulebooks, is NOT two-way communication. It goes one direction only, writer to reader. So you have to make assumptions about what your audience will and will not understand. The burden is on the writer to estimate the reader's knowledge and write accordingly.
If I write a book for children to be published in Australia, and mention the United States Electoral College without explaining what it is, and most of the Aussie kids reading my book assume I'm talking about an institution of higher learning--that isn't their fault. It's my fault. As the writer, I know (or ought to!) that Australian children aren't going to know about the intricacies of the U.S. political system. If knowledge of the Electoral College is at all important to the story, my book should explain what the heck it is.
On the other hand, if I write a book for political science professors in the U.S., then I can talk about the Electoral College without including an explanation. It is safe for me to assume that my audience knows what the Electoral College is.
The key is knowing your audience. As I said--if I use a word to mean Y, when I
know my audience expects it to mean X, it's my fault if they don't get what I'm saying. If I
don't know what my audience expects, then the question becomes whether I could reasonably have been expected to know. If the answer is yes, it's still my fault for failing to learn about my audience. If the answer is no, then and only then should the audience be held responsible.
As a rule, if one is addressing a large audience, and most of the audience does not understand, it is much more likely to be the speaker who's at fault.