Triannual is a related term of triennial.
As adjectives the difference between triannual and triennial
is that triannual
is happening three times each year while triennial
is happening every three years.
As a noun triennial is
a third anniversary.
Other Comparisons: What's the difference?
Happening three times each year.
* To avoid confusion between "triennial", once every three years, and "triannual", three times in one year, it is often better to substitute a less ambiguous phrase such as "three times a year" or "every four months".
* triennial (every three years) which is sometimes confused with triannual (usually every four months).
* biennial (every two years).
* biannual (twice a year).
** semiannual (also twice a year).
Happening every three years.
- triennial elections
Lasting for three years.
- triennial''' parliaments; a '''triennial reign
* (rare) trieterical
A third anniversary.