Only here in New Testament. From Τάρταρος, Tartarus. It is strange to find Peter using this Pagan term, which represents the Greek hell, though treated here not as equivalent to Gehenna, but as the place of detention until the judgment.
Chains of darkness (σειραῖς ζόφου)
Σειρά is a cord or band, sometimes of metal. Compare Septuagint, Proverbs 5:22; Wisd. of Sol. 17:2, 18. The best texts, however, substitute σιροῖς or σειροῖς, pits or caverns. Σιρός originally is a place for storing corn. Rev., pits of darkness.
Of darkness (ζόφου)
Peculiar to Peter and Jude. Originally of the gloom of the nether world, So Homer:
“These halls are full
Of shadows hastening down to Erebus
Amid the gloom (ὑπὸ ζόφον).”
Odyssey, xx., 355.
When Ulysses meets his mother in the shades, she says to him:
“How didst thou come, my child, a living man,
Into this place of darkness? (ὑπὸ ζόφον).”
Odyssey, xi., 155.
Compare Jud 1:13. So Milton:
“Here their prison ordained
In utter darkness, and their portion set
As far removed from God and light of heaven
As from the centre thrice to the utmost pole.”
Paradise Lost, i., 71-74.
And Dante:
“That air forever black.”
Inferno, iii., 829.
“Upon the verge I found me
Of the abysmal valley dolorous
That gathers thunder of infinite ululations.
Obscure, profound it was, and nebulous,
So that by fixing on its depths my sight
Nothing whatever I discerned therein.”
Inferno, iv., 7, 12.
“I came unto a place mute of all light.”
Inferno, v., 28.
To be reserved (τηρουμένους)
Lit., being reserved. See on 1Pe 1:4, “reserved in heaven.”