First, "eternal" is in fact a direct descendent of the Greek word "αἰών" by way of the Latin "aeternus" = "aevum" + "ternus". When you say "eternal", you could also debate on historical grounds whether you are referring to a delimited or unbounded time. Greek is polysemic and "αἰών" is no exception, but in practice, the indefinite sense is quite common for "αἰών" and generally obvious by context. Consider:
(Platon) "ἀνώλεθρον... ἀλλ᾽ οὐκ αἰώνιον" = indestructible but not eternal
Now, are there other ways of expressing infinite time in ancient Greek? Many:
- Periphrastic expressions
"τὸ αεί" = using the adverb for always as a substantive
"διὰ παντός" = for ever
(Platon) "περὶ τὰ ἀεὶ ὄντα" = concerning the ever being
(Herodotus) "ἔργον χρήσιμον ἐς τὸν πάντα χρόνον" = a work that was useful for all time
etc.
- ἀίδιον
(Aristotle) "ὥστ᾽ οὐδὲ τὸ ἀγαθὸν μᾶλλον ἀγαθὸν τῷ ἀίδιον εἶναι" = so therefore the good is no better a good by its being eternal.
- ἀειγενής (the ever-being)
(Xenophon) "ἰσήλικος τοῖς ἀειγενέσι θεοῖς" = the same age as the eternal gods
- ἀέναος (the ever-flowing)
(Aristophanes) "ἀέναοι Νεφέλαι" = the eternal clouds
- ἄφθιτος (unperishing)
(Pindar) "λῦσε δὲ Ζεὺς ἄφθιτος Τιτᾶνας" = Zeus eternal freed the Titans
etc.
Answer from philippos on Stack ExchangeVideos
First, "eternal" is in fact a direct descendent of the Greek word "αἰών" by way of the Latin "aeternus" = "aevum" + "ternus". When you say "eternal", you could also debate on historical grounds whether you are referring to a delimited or unbounded time. Greek is polysemic and "αἰών" is no exception, but in practice, the indefinite sense is quite common for "αἰών" and generally obvious by context. Consider:
(Platon) "ἀνώλεθρον... ἀλλ᾽ οὐκ αἰώνιον" = indestructible but not eternal
Now, are there other ways of expressing infinite time in ancient Greek? Many:
- Periphrastic expressions
"τὸ αεί" = using the adverb for always as a substantive
"διὰ παντός" = for ever
(Platon) "περὶ τὰ ἀεὶ ὄντα" = concerning the ever being
(Herodotus) "ἔργον χρήσιμον ἐς τὸν πάντα χρόνον" = a work that was useful for all time
etc.
- ἀίδιον
(Aristotle) "ὥστ᾽ οὐδὲ τὸ ἀγαθὸν μᾶλλον ἀγαθὸν τῷ ἀίδιον εἶναι" = so therefore the good is no better a good by its being eternal.
- ἀειγενής (the ever-being)
(Xenophon) "ἰσήλικος τοῖς ἀειγενέσι θεοῖς" = the same age as the eternal gods
- ἀέναος (the ever-flowing)
(Aristophanes) "ἀέναοι Νεφέλαι" = the eternal clouds
- ἄφθιτος (unperishing)
(Pindar) "λῦσε δὲ Ζεὺς ἄφθιτος Τιτᾶνας" = Zeus eternal freed the Titans
etc.
(I'm not writing these words in Greek, which can be read by people who don't read Greek)
aion and aionios are for a period with a beginning and an end. They never denoted unending.
Josephus reports that the Pharisees taught "regarded the penalty of sin as torment without end, and they stated the doctrine in unambiguous terms. They called it eirgmos aidios (eternal imprisonment) and timorion adialeipton (endless torment)." These words were available and clearly in common use since the Pharisees taught the people their doctrines. (See J W Hansen - Universalism - Prevailing doctrine of the Christian Church during the first 500 years. pg36.)
So, clearly there were words to indicate eternal. It seems Strong's and others had other religious reasons for injecting meanings into words for which there is no literary basis.