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vigentennial

American  
[vahy-jen-ten-ee-uhl] / ˌvaɪ dʒɛnˈtɛn i əl /

noun

  1. a 20th anniversary.

  2. a celebration, meeting, reunion, etc., commemorating such an anniversary.


Etymology

Origin of vigentennial

< Latin vīgēn ( ī ) twenty each + (cen)tennial