trimillennial

noun, adj — 2 senses

noun

Etymology From Latin trimillennialis, from tri- + mill- (“thousand”) + Latin enni(us) (“year”) + -al.

The 3,000th anniversary of an event or happening.

adj

Etymology From Latin trimillennialis, from tri- + mill- (“thousand”) + Latin enni(us) (“year”) + -al.

Occurring every three thousand years

Entry derived from the Wiktionary, under licence CC BY-SA 4.0 — list of authors.