What about the phrase "ages of the ages" used in Revelation? To me, it seems to mean "Some ages of all the ages." or something like that. For fun, I decided to see how "eternal" and "forever" would be written in Japanese. Japanese itself is a very isolated language, but it has lots of influences from Chinese and English.
They have a single kanji meaning "eternal", but it can also mean "lengthy" or "long". It's "永", but they don't write it by itself. No, the first entry I get with my dictionary when I search for "eternal" is "fushi" or "不死" it means "eternal life". The kanji literally mean "non-death". Amazingly, the next entry is "kou" or "劫", it's a Buddhist term meaning roughly the same as "eon" or "age". Funny, isn't it? "Nagano, or "永の" means "eternal", but not in and of itself. It means "eternal-" meaning a word has to come after it to signify an eternal-something.
So I try looking for the word "forever". The first word is "chiyo" or "千世". It means "thousand years", "very long period", or "forever". All the other words for "forever" are just a kanji meaning "very long period", but repeated, so it's written twice. I don't know what all this means, but it's interesting.