- trimillennial
- 1. nounThe 3,000th anniversary of an event or happening.2. adjectiveOccurring every three thousand years
Wikipedia foundation.
Wikipedia foundation.
millennial — 1. adjective /mɪˈlɛniəl/ a) Referring to the 1,000th anniversary of an event or happening: millennial fair. b) Occurring every thousand years. See Also: bimillennial, decamillennial, millennium, quadrimillennial, trimillennial 2 … Wiktionary