1. Continuing three years; happening every three years.

Nuttall's Standard dictionary of the English language By Nuttall, P.Austin

• prennial,
• tribunial,
• periennial,
• triennale,
• trenial,
• rriennial,
• friennial,
• griennial,
• trienial,
• triennnial,
• tryennial,
• trienniel,
• tricenial,
• triennialy,
• trivebrial,
• troopiall,
• Trennal,
• splennial,
• triogniae,
• Triceanial

• trenail,
• trenholm,
• train oil,
• treenail,
• trunnell,
• trunnel,
• trainload.

The adjective form of the word "triennial" is "triennial".

The plural of the "triennial" can be the "triennials".

The singular of the "triennial" can be the "triennial".