The correct spelling is "triannual" (occurring three times each year).
Triannual.
Biannual Triannual
triannual
triannual
Similarly to biannual, the word "triannual" may be used to describe something that occurs three times per year, though it is not used as often as biannual or quarterly and therefore is not as widely known. In contrast, the word "triennial" is used to describe something that occurs every three years.
Triennial means three years-- 36 months. Triannual means: occurring three times per year. How's that for unambiguous? Triannual doesn't really imply that the event described must happen exactly every 4 months-- only that it happens three times during a year.
The term used is 'triannual'. It should not be confused with triennial, which means the journal is published only once in every three years.
Triangle Tripod Triad Trilogy Triceratops Triathlon Triathlete Trillion Tricycle Triassic Trigram Trisect Triacid Triatomic Triannual
Quarterly (in other words 12 months divided by 4)
There is disagreement on whether there even exists a proper, unambiguous term for "every four months." Many use triannualfor the purpose. There is some logic to this, since biannualmeans twice yearly, whereas biennial means every two years, and triennial means every three years. But some dictionaries, ones that do list triannual, list it as a synonym for triennial ("every three years") while at the same time giving it the meaning of "three times yearly" And although biennial and biannual are well defined, they are often confused in usage. And in horticulture, biannualrefers to a two-year cycle. Some have suggested the awkward term quadrimonthly, while others suggest the straightforward thrice-yearly. But whatever we do we have to be clear. Even the writers who use triannual often attach the definition alongside it, because they know it can be misunderstood.
The word meaning three people (as in a band) is trio.Some other words using the Greek prefix "tri-" are triad, triangle, triannual, triathlon, tricuspid, tricycle, trident, trinary, triplets, tripod, and trisect.