1 adj Something that is eternal lasts for ever.
Whoever believes in Him shall have eternal life., ...the quest for eternal youth.
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eternally adv ADV adj, ADV with v
She is eternally grateful to her family for their support...
2 adj If you describe something as eternal, you mean that it seems to last for ever, often because you think it is boring or annoying.
(=interminable, never-ending)
In the background was that eternal hum.