- Adjective. (Christianity) Pertaining to the belief in an impending period of one thousand years of peace and righteousness associated with the Second Coming of Christ. (defdate, from 17th c.) .
- Adjective. Pertaining to any of various religious or social movements which believe in a coming radical change to existing world order; utopian, apocalyptic. (defdate, from 20th c.) .
- Adjective. (rfv-sense) Of or pertaining to a thousand years.
- Noun. A person who believes in an apocalyptic millennium, an Adventist.