Wiktionary
n. (context Christianity English) A view in Christian eschatology that rejects the claimed future thousand-year physical reign of Jesus Christ on the earth, in opposition to premillennial and some postmillennial views of the Book of Revelation, chapter 20, claiming instead that the number of years in Revelation 20 is a symbolic number and that Christ's eventual physical reign will be permanent.
Wikipedia
Amillennialism ( Greek: a- "no" + millennialism), in Christian eschatology, involves the rejection of the belief that Jesus will have a literal, thousand-year-long, physical reign on the earth. This rejection contrasts with premillennial and some postmillennial interpretations of chapter 20 of the Book of Revelation.
The amillennial view regards the "thousand years" mentioned in Revelation 20 as a symbolic number, not as a literal description; amillennialists hold that the millennium has already begun and is identical with the current church age. Amillennialism holds that while Christ's reign during the millennium is spiritual in nature, at the end of the church age, Christ will return in final judgment and establish a permanent reign in the new heaven and new earth.
Many proponents dislike the name "amillennialism" because it emphasizes their differences with premillennialism rather than their beliefs about the millennium. "Amillennial" was actually coined in a pejorative way by those who hold premillennial views. Some proponents also prefer alternate terms such as nunc-millennialism (that is, now-millennialism) or realized millennialism, although these other names have achieved only limited acceptance and usage.
Usage examples of "amillennialism".
What is the difference between premillennialism, amillennialism, and post-millennialism?