"Eternity" is God, whose manifestations have no beginning and no end.

"Eternity" of God is His sovereignty over time, flowing without beginning or end. It is the infinity of God's Life and Being, God's dwelling in the everlasting present.  

"Eternity" of God is a timeless category, a form of God's existence,

"Eternity" of God is the infinite existence of God - beyond time and space, infinite, endless, unceasing, constant, uninterrupted, in all ages, always.        

 "Eternity" is the Laws, Covenants, Commandments, Resolutions of God, which always remain eternal, constant, unchanging, no matter what time and historical circumstances of peoples' lives, and which God has never changed and never changes.

"Eternity" is the existence of a godly man who has passed from a righteous life to Eternal Life; his existence beyond matter, time, and space. 

Negative meaning:

"Eternity" is the state of eternal non-existence, which befalls with irreversible consequences the godless man who denies God; the lawless man who opposes His Will, the ungodly man who willfully violates His Commandments, the slandererer of God.