I agree. According to the Greek/English dictionary section of Strong's Exhaustive Concordance there are three Greek words that translate into eternal and/or eternity in English and are found in the Greek NT manuscripts.
There appears to be some minor degree of ambiguity concerning the # 2 word. It is the only one of the three Greek words that can be translated into an English word or phrase that can define any period of time less than eternity, although the word "age" which is the preferred usage in the listed preferences, can be used to either specify a period of time as in the phrase "the age of reason" or to imply "eternity" as in this phrase of an old hymn, "throughout endless ages". IOW it can just as easily be used to mean "eternity" or "eternal" without doing harm to it's preferred use as "age".
Since of course I don't have the Greek alphabet on my keyboard, the Greek words are typed in English letters that best define the sound of the Greek word. The preferred or most common translation of each Greek word is listed first followed by alternate but less common meanings:
1. ah-eye = always, ever, duration.
2. aheek-mal-o-tid-so = age, perpetuity, course, eternal, evermore, without end
3. Ahee-o-nee-us = perpetual, past and future, eternal, ever, everlasting.
I'm not a linguist nor do I play one on TV. But my cousin has a masters in linguistics and works for a Washington D.C. based company that translates obscure and/or "dead" languages from around the world into English for US government agencies including the CIA. If my amateurish effort at translating the Greek according to a commonly used Greek/English dictionary is insufficient to settle the issue, I might be able to get a much more comprehensive translation of those words from her by email, possibly including a history of their evolution into 1st century Greek from other more ancient languages.
I referred to a book in the original thread post with the title of "Church Doctrines: Right or Wrong? (You Decide)" and find that the author did quite an extensive investigation into the Greek terms "aion, aionias," the Hebrew term "olam," and other related terms." In one of his appendix's he has a whole list of words concerning "time" that one should consider, and how the term "eternal and eternity" entered into the Bible. I think one can get that book at the following places: The Publisher, iuniverse.com; amazon.com; and b&n.com (Barn's and Noble).
BTW, you can find the Greek font "spionic" on the Web and install it into your word processing programs. It's easy to use. I've tried to use it here via "copy and paste" but it doesn't work.