'Eternal' in the Bible

You also know that the angels who did not keep within their proper domain but abandoned their own place of residence, he has kept in eternal chains in utter darkness, locked up for the judgment of the great Day.

So also Sodom and Gomorrah and the neighboring towns, since they indulged in sexual immorality and pursued unnatural desire in a way similar to these angels, are now displayed as an example by suffering the punishment of eternal fire.

wild sea waves, spewing out the foam of their shame; wayward stars for whom the utter depths of eternal darkness have been reserved.

maintain yourselves in the love of God, while anticipating the mercy of our Lord Jesus Christ that brings eternal life.