She promised to love him for all 'eternity'. [=to love him forever]
We suffered through an 'eternity' of delays during the lawsuit.
They believed that sinners would spend 'eternity' in hell.
(..) - We have an understanding. - Good. Everything would be out in the open if Corleone dies. Play for time, Keinszig. A habit born of a long contemplation of eternity. - Forget about it, Vinnie. - Why? It's a simple hit. I'd love to smack Joey Zasa and then whack the fag. But it's impossible. (..)1990 The Godfather Part III