1. happening every three years
2. lasting for three years

1. an event that occurs every three years

Examples

• The art museum hosts a triennial exhibition of contemporary works.
• The company conducts triennial reviews of its strategic plan.
• She was elected to a triennial term on the board of directors.
• The triennial conference brings together experts from around the world.
• The organization’s triennial budget covers a three-year period.
• The Venice Biennale is actually held every two years, unlike the triennial in São Paulo.
• The triennial celebration marks the town’s founding anniversary.