Second Death

DEATH, SECOND, the tr. of most Eng. VSS of the Gr. phrase ὁ δεύτερος θάνατος, found only in Revelation 2:11; 20:6, 14; 21:8. It refers to the eternal judgment of God upon sin which occurs after physical death. It is therefore synonymous with such other apocalyptic expressions as “lake of fire,” “winepress of wrath,” “darkness,” et al. The phrase is characteristic of the repetitive and reciprocal nature of the structure of Revelation, wherein ordinal numbers e.g. first, second, third, etc., play an important part in its presentation.

International Standard Bible Encyclopedia (1915)

An expression, peculiar to the Book of Rev.(Re 2:11; 20:6,14; 21:8) in Scripture, denoting the final penalty of the unrighteous; parallel with another expression likewise peculiar, "the lake of fire," in Re 20:14; 21:8. See Eschatology of the New Testament.