1847, in the meaning defined above
Latin, from tri- + annus year — more at annual
Time Traveler for triennium
See more words from the same year
Cite this Entry
“Triennium.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/triennium. Accessed 18 Jan. 2022.
See Definitions and Examples »
Get Word of the Day daily email!
Farm Idioms Quiz
Test your vocabulary with our 10-question quiz!
A daily challenge for crossword fanatics.
Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!
Top 10 Latin Phrases
Here's where those fancy shades get their names.
Have we piqued your interest?
Because 200 seemed like overkill
A simple trick to keep them separate
How 'literally' can mean "figuratively"
How to use a word that (literally) drives some pe...
The awkward case of 'his or her'
New Year, Recondite Vocabulary
Take the quiz
Tough words and tougher competition.