"So I wondered if the entire debate over the use of the term "Deciduous" could have been based on a non agreement over the actual definition of the word (not likely)?"
If you look in any reference for antonyms to evergreen you will find that the opposite word is deciduous. Dormant means not growing, and the opposite of that is growing, not evergreen. The problem with deciduous is that so many general references give trees that drop their leaves in fall as an example. That doesn't mean it's the only definition, just an example. Basically a deciduous plant has all its leaves die at once every year, whether they fall off immediately or not as explained in my earlier post (look up marcescence in oak and beech).
