What does triennially mean?
Triennially is an adverb meaning every three years or at three-year intervals. It is formed from the related adjective triennial and is commonly used for events that recur on a relatively infrequent schedule, such as conferences, inspections, reviews, reports, and major assessments. The word is neutral to formal in register and appears particularly often in institutional, academic, legal, and administrative writing. Although it can sometimes imply that an event occurs in the third year of a sequence, its basic meaning is simply that three years pass between one occurrence and the next. Triennially is especially useful because it conveys this precise interval in a single word, avoiding the longer constructions “every three years” and “once every three years.” Its Latin ancestry is transparent: triennially ultimately derives from a word meaning a period of three years, combining the numeral element for three with the Latin word for year.
adverbEvery three years; at intervals of three years.
- At three-year intervals; every three years.
"The international conference is held triennially, with the next meeting scheduled for 2029."
"The awards are presented triennially to recognize outstanding work in the field."
"The building undergoes a detailed safety inspection triennially."
Triennially keeps a three-year rhythm: its Latin roots combine “three” and “year” into a perfectly periodic instruction.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does triennially come from?
Triennially comes from triennial, which is derived from Latin triennium, meaning a period or term of three years. Latin triennium was formed from the combining element tri-, meaning three, and annus, meaning year; the numeral element is related to Latin ter, the root behind words such as ternary. The adverbial ending -ly was added in English to triennial to indicate manner or frequency.
Related word forms
How triennially is actually used
The word is neutral to formal in tone and is especially common in institutional, academic, and administrative contexts. It describes a three-year interval rather than necessarily referring to every third year in a numbered sequence.
Easily confused with triennially
Triennially means every three years, whereas biennially means every two years.