Ὄγδοος (Strong’s 3590) designates what is “eighth” in an ordered series. In Scripture the ordinal never functions as mere chronology; it consistently serves covenant, salvation-historical, or eschatological purposes that underscore new beginnings established by God.

Occurrences in the New Testament

1. Luke 1:59 – the eighth day of John’s circumcision.
2. Acts 7:8 – Isaac circumcised on the eighth day.
3. 2 Peter 2:5 – Noah preserved “the eighth” with seven others.
4. Revelation 17:11 – the beast that “is an eighth” king.
5. Revelation 21:20 – the eighth foundation stone of the New Jerusalem.

Old Testament Background and Covenant Significance

The eighth day is introduced as a divinely fixed marker of covenant renewal. Circumcision was commanded “on the eighth day” (Genesis 17:12; Leviticus 12:3), the priests were consecrated on the eighth day (Leviticus 9:1), and cleansed lepers presented offerings on the eighth day (Leviticus 14:10). These patterns prepare the reader to see “eighth” as the day in which the LORD affirms covenant relationship and inaugurates a cleansed or newly consecrated state.

Salvation-Historical Themes in the Five New-Testament Occurrences

Luke 1:59 and Acts 7:8 echo Genesis 17, anchoring the births of John the Baptist and Isaac in the Abrahamic covenant. “On the eighth day” God’s previous promise is publicly ratified in the flesh of the child. That Luke records the same practice for Jesus (Luke 2:21, using a different form) confirms His lawful inclusion in Israel and anticipates His role as fulfiller of the covenant.

2 Peter 2:5 uses ὄγδοος in a personal sense: God “protected Noah, a preacher of righteousness, among eight.” Here “the eighth” marks Noah as the head of a new humanity. After judgment, eight persons step onto a cleansed earth, foreshadowing the re-creation theme completed in Christ (compare 1 Peter 3:20-21).

Revelation 17:11 twists the positive script. The beast “is an eighth king, belonging to the seven.” The ordinal signals an illicit parody of God’s pattern: a counterfeit new beginning that culminates in destruction. John thus contrasts the dragon’s pseudo-eighth day with the true, eternal eighth day that appears two chapters later.

Revelation 21:20 resumes holy imagery. The “eighth” foundation is beryl, part of a twelve-stone array that recalls the breastpiece of the high priest (Exodus 28:17-20). In the consummated City each ordinal stone proclaims the completed, perfected people of God; the eighth, set midway, underscores continuity between old and new creations.

Theological and Typological Implications

New Creation: The octave structure (seven days completed, an eighth that begins afresh) becomes shorthand for resurrection life—the “first day of the week,” yet transcending the old order. Jesus rose on the first/eighth day (Matthew 28:1) and the early church gathered on that day (Acts 20:7; 1 Corinthians 16:2), living ritually in the perpetual eighth day.

Covenant Seal: Every NT appearance of ὄγδοος relates back to covenant faithfulness—whether Abrahamic (circumcision), Noahic (preservation), Mosaic (priestly stones), or the climactic New Covenant (Resurrection, New Jerusalem).

Judgment and Counterfeit: Revelation 17:11 warns that evil attempts its own “eighth,” promising a new order apart from God. Scripture exposes such claims and consigns the counterfeit eighth to perdition, preserving the true new creation for the Lamb and His people.

Practical and Ministerial Applications

• Baptism and Lord’s Day worship reflect the eighth-day pattern: pastors encourage believers to see Sunday gatherings as weekly participation in resurrection life.
• Teaching on Genesis 17 and Luke 1 builds confidence that God keeps covenant across generations.
• Preaching 2 Peter 2:5 offers assurance that even in global judgment God preserves His remnant and establishes a fresh start.
• Revelation’s dual eighths equip the church to discern between authentic renewal in Christ and deceptive worldly utopias.
• The gemstone list in Revelation 21 motivates believers toward holiness—each life laid in the wall of the eternal city.

Summary

Strong’s 3590 does more than count to eight. Woven through Scripture, the term marks covenant inauguration, re-creation after judgment, and the final consummation of redemption, all pointing to Jesus Christ, in whom the true eighth day dawns forever.