I have heard that the Greek word aiōnios is more literally translated "age-long", the adjective form of aiōn meaning "age". Aiōnios is translated as "eternal" in most bibles. I'm thinking specifically of Matthew 25:46. Were there any other words or phrases in use in Greek at the time that more clearly expressed the concept "eternal" and that the author specifically was not using in this passage?
What words existed in Greek to express the concept “eternal”?
Far and away the most common word for "eternal" in the Greek is αἰώνιος. Of the 68 occurrences of "eternal in the (AV), this word accounts for 63 of those instances.
Other Greek words being translated as "eternal" are:
The other two (2) instances of a Greek word being translated as "eternal," are ἀνάθεμα (anathema), which, in both instances equates to being eternally cursed.