The ancient Greek phrase for the abode of the dead, synonymous with Gehenna.

This word occurs only one time in the New Testament, 2 Peter 2:4, and is translated as “hell” in the NASB. According to Thayer’s Greek Definitions, tartaroo is “the name of the subterranean region, doleful and dark, regarded by the ancient Greeks as the abode of the wicked dead, where they suffer punishment for their evil deeds; it answers to Gehenna of the Jews.” The usage of a Greek term would be consistent with the epistle’s likely destination, a church mixed with Jews and Gentiles1.

1Kenneth Gangel. Walvoord, John F., The Bible Knowledge Commentary (Colorado Springs: Victor Books, 1983), 862.