- a period of ten years; a decade.
Origin of decennium
From Latin, dating back to 1675–85; see origin at decennial
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
- a less common word for decade (def. 1)
Word Origin for decennium
C17: from Latin, from decem ten + 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