2000s /tuː ˈθaʊ.zəndz/ noun[plural only]3 •The decade that began on January 1, 2000 and ended on December 31, 2009. •The century that began on January 1, 2000 and ends on December 31, 2099.The people of the late 19th century approached the 20th with the same awe with which we see the 2000s. — 1980 •(rare) The millennium that began on January 1, 2000 and ends on December 31, 2999.What Roman numeral might you find in the cornerstone of a building built in the year 2000? MM – the mark of the new millennium, a move from the 1000s to the 2000s. — 1999
