mə̇ˈlenēəm noun
( plural millen·nia -ēə ; or mil·lenniums )
Etymology: New Latin, from Latin mille thousand + -ennium (as in biennium period of two years) — more at biennial
1.
a. : a period of 1000 years
records dating back several millennia
b. : a 1000th anniversary or its celebration
2.
a. : the thousand years mentioned in Revelation 20 during which holiness is to be triumphant and Christ is to reign on earth
b. : a period of prevailing virtue or great happiness or perfect government or freedom from familiar ills and imperfections of human existence