millennial

UK: /mɪˈlenɪəl/ US: (mil len′ē əl)

WordReference Random House Unabridged Dictionary of American English © 2026

mil•len•ni•al  (mil len′ē əl), adj. 

1. of or pertaining to a millennium or the millennium.
2. worthy or suggestive of the millennium.

• millenni(um) + -al¹ 1655–65

mil•len′ni•al•ly, adv. 

Collins Concise English Dictionary © HarperCollins Publishers::

millennial / mɪˈlɛnɪəl/ adjective of or relating to the millennium of or relating to a period of a thousand years noun a member of the generation who reached adulthood around the year 2000

milˈlennialist noun

WordReference Random House Learner's Dictionary of American English © 2026

mil•len•ni•um /mɪˈlɛniəm/   n. [countable] , pl. -ni•ums, -ni•a 

/-niə/.  
1. a period of 1000 years:
   to view history through the millenia.

mil•len•ni•al, adj. 

WordReference Random House Unabridged Dictionary of American English © 2026

mil•len•ni•um  (mi len′ē əm), n., pl. -ni•ums, -ni•a 

(-nē ə). 
1. a period of 1000 years.
2. Bible, Religion 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.

• Neo-Latin, equivalent. to Latin mill(e) a thousand + -ennium, extracted from biennium, triennium, etc.
• 1630–40