- millennium
- 1638, from L. mille "thousand" + annus "year" (see annual); formed on analogy of biennium, triennium, etc. First in Eng. in sense of "1,000-year period of Christ's anticipated rule on Earth" (Rev. xx.1-5); hence millenarian (1552) "one who believes in the coming of the millennium." Sense of "any 1,000-year period" first recorded 1711.