What did Jesus say about Hell?

Hell’s fire is eternal. 

“If your hand or your foot causes you to stumble, cut it off and throw it away. It is better for you to enter life maimed or crippled than to have two hands and two feet and be thrown into eternal fire.”
Matthew 18:8

Hell’s punishment is eternal. 

“Then they will go away to eternal punishment, but the righteous to eternal life.”
Matthew 25:46

Hell is the second death.  The first death permanently ends our life on earth.  The second death makes our separation from God permanent.

“Anyone whose name was not found written in the book of life was thrown into the lake of fire.”
Revelation 20:15

“But the cowardly, the unbelieving, the vile, the murderers, the sexually immoral, those who practice magic arts, the idolaters and all liars- they will be consigned to the fiery lake of burning sulfur.  This is the second death.”
Revelation 21:8

When it comes to these bible verses about hell, what is the word used in the original language for “eternal”?

The Greek word used for “eternal” referring to punishment is the same word used for “eternal” referring to life.  It’s used for both in Matthew 25:46.  It’s used in John 3:16, 3:36, and Romans 3:23

Consider John 3:36.

“Whoever believes in the Son has eternal life, but whoever rejects the Son will not see life, for God’s wrath remains on him.”

“Will not see life” sounds definitive, and “wrath of God remains” is contrasted with eternal life, making “remains” permanent.  While it doesn’t say “eternal punishment” it certainly infers it by a “remaining wrath of God.”

“And this is the testimony:  God has given us eternal life, and this life is in His Son.  He who has the Son has life; he who does not have the Son of God does not have life.”
1 John 5:11-12

If everyone eventually makes it to heaven, then “does not have life” doesn’t make sense.

“Just as man is destined to die once, and after that to face judgement.”
Hebrews 9:27

Die once.  Judged once.  What’s the verdict.

Different forms for the Greek word for eternal are used to refer to “age” as in a period of time, but every time the specific form is used, it refers to eternal.

Nowhere when Jesus speaks of hell do you get the impression that it’s temporary.  The word “eternal” might not be used with it, but the sense of finality is there.

Hell is real.
Hell is eternal.
Hell is permanent.
Hell is separation from God.
Hell is the wrath of God.
Hell is anguish, torment, regret.
Hell is motivation.

“Rescue others by snatching them from the flames of judgment.”
Jude 1:23