A period of time consisting of one thousand years. / (Christianity) The period of one thousand years during which Christ will reign on earth (according to Millenarianist interpretations).

plural of millennium

(computing) A design flaw in computer systems that represented years as two digits (e.g. 84 for 1984), which could cause date calculations to fail if they involved years later than 1999.

A large building at Greenwich in London, the largest single roofed structure in the world; now renamed "O2".

plural of light millennium

(astronomy, physics) A unit of length equal to the distance light travels in one millennium.

(historical) Any of a set of eight international development goals established by the United Nations in 2000, scheduled to be achieved by 2015.

plural of Millennium Development Goal