'Second Death' in the Bible

He that has an ear, let him hear what the Spirit says to the assemblies. He that overcomes shall in no wise be injured of the second death.

Blessed and holy he who has part in the first resurrection: over these the second death has no power; but they shall be priests of God and of the Christ, and shall reign with him a thousand years.

and death and hades were cast into the lake of fire. This is the second death, even the lake of fire.

But to the fearful and unbelieving, and sinners, and those who make themselves abominable, and murderers, and fornicators, and sorcerers, and idolaters, and all liars, their part is in the lake which burns with fire and brimstone; which is the second death.