of or for 20 years.
occurring every 20 years.
Origin of vicennial
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
occurring every 20 years
relating to or lasting for a period of 20 years
Word Origin for vicennial
C18: from Late Latin vīcennium period of twenty years, from Latin vīciēs twenty times + -ennium, from annus year
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012