/mi len"ee euhm/ , n. , pl. millenniums, millennia /-nee euh/ .
1. a period of 1000 years.
2. the millennium , the period of a thousand years during which Christ will reign on earth. Rev. 20:1-7.
3. a period of general righteousness and happiness, esp. in the indefinite future.
4. a thousandth anniversary.
[ 1630-40; mill ( e ) a thousand + -ennium, extracted from BIENNIUM, TRIENNIUM, etc. ]