This word is found but once in the inspired Scriptures, at 2[bless and do not curse]Peter 2:4. The expression throwing them into Tartarus is from the Greek verb tar·ta·ro′o and so includes within itself the word Tartarus. It is a prisonlike, abased condition into which God cast disobedient angels in Noahs day.
A parallel text is found at Jude 6. These angels forsook their own proper dwelling place. Peter speaks of the spirits in prison, who had once been disobedient when the patience of God was waiting in Noahs days, while the ark was being constructed. (1 Peter 3:19,[bless and do not curse]20) This directly links the matter to the account at Genesis 6:1-4 concerning the sons of the true God who abandoned their heavenly abode to cohabit with women in pre-Flood times.
From these texts it is evident that Tartarus is a condition rather than a particular location, inasmuch as Peter, on the one hand, speaks of these disobedient spirits as being in pits of dense darkness, while Paul speaks of them as being in heavenly places from which they exercise a rule of darkness as wicked spirit forces. (2 Peter 2:4; Ephesians 6:10-12) The dense darkness similarly is not literally a lack of light but results from their being cut off from illumination by God as renegades and outcasts from his family, with only a dark outlook as to their eternal destiny.
Tartarus is, therefore, not the same as the Hebrew Sheol or the Greek Hades, both of which refer to the common earthly grave of mankind. This is evident from the fact that, while the apostle Peter shows that Jesus Christ preached to these spirits in prison, he also shows that Jesus did so, not during the three days while buried in Hades, but after his resurrection out of Hades.-1 Peter 3:18-20.
Likewise the abased condition represented by Tartarus should not be confused with the abyss into which Satan and his demons are eventually to be cast for the thousand years of Christs rule. (Revelation 20:1-3) Apparently the disobedient angels were cast into Tartarus in Noahs days (1 Peter 3:20), but some 2,000 years later we find them entreating Jesus not to order them to go away into the abyss.-Luke 8:26-31.