This is an interesting question. The simple answer is that the Greek AIWN basically means 'an age' or period of time. It is the context and combination of words used that gives the meaning of everlasting. A good example of this would be the Hebrew word for 'god', which is 'EL' (simply means "mighty one"). This title is applied to our almighty Creator. The word itself does not explain that He is almighty, it is the context that speaks concerning his almighty attributes.
AIWN means age, and the combination of "unto the ages of the ages" in the Greek text most certainly in all appearances seems to denote 'for ever'.
Yet there are instances that it is singular, like (end of the "AIWN"). In this context it definitely don't mean 'for ever'. Also when Paul says "Who shall be punished with age-lasting ruin from the presence of the Master...". This is at the end of this age, and judgment day still has to take place. This is quite simple those who belong to the Saviour will obtain age-lasting life (which simply means age-lasting life in the age to come). This is the promise of rest and peace on earth before heaven and earth passes away. And those who Jude spoke those who have spoken "harsh words" against His greatness will be send from His presence for a whole age, where they will not obtain rest. This is the judgment at the end of this age and not yet the final judgment so they don't at that point go into "eternal punishment". It is the "smoke of their trial" that is said to go up "unto the ages of the ages".
As for age-lasting life of the believer. Again the context makes it clear, as the Anointed One himself said "in the age to come age-lasting life". These are those resurrected at the end of this age and will live a thousand years on earth, taking part in the promise of rest before the earth is destroyed. Like Paul says "And to you who are troubled rest with us when our Master Yahusha (Jesus) will be revealed from heaven". Now everlasting life is not explained thru the Greek word AIWNION ( age-lasting) on its own. It is explained thru the revelation that mortality shall put on immortality, and these shall not taste death again, and finally at the end of Revelations "they will reign with Him unto the ages of the ages",after the age wherein they already obtained age-lasting life, after the day of judgent. Age-lasting therefore simply means it goes on continuously in that particular age. Sodom and Gomorrah experiences the justice of age-lasting fire as Jude mentions, yet they shall rise on the day of judgment and shall condemn other generation that were better off than them.
How great is salvation if its worth going thru age-lasting judgment to obtain? (as the case of Sodom and Gommorah)