triennial

/tɹaɪˈɛniəl/

//tɹaɪˈɛniəl// adj

"triennial" is a 9-letter English headword indexed on PlainSpell.

The verdict

“triennial” is uncommon English (frequency #53,921 among 3,151 “T” headwords), classed as an adjective. The kind of spelling people second-guess.

#53,921
frequency rank, English
3,151
“T” headwords

According to Wiktionary data (CC BY-SA, analyzed September 3, 2026) - Happening every three years.

Corpus desk

Index EN-triennial · triennial · English

triennial · rank #53,921 · 0 variants · 0 confusables

  • FREQ-RARE #53,921
  • LEN-LONG 9 letters
  • VOW-4 4 vowels
  • CONFUS-0 No pairs
  • VAR-0 0 variants
  • BOOK-MID 3,151
  • PHOTO-FINISH tricolor

Nearest frequency peer: tricolor (-1 rank slots)

Read with this headword: Spelling guide for this pattern

Desk codes from Wiktionary headword shape, FrequencyWords rank tier, confusable-pair count, generated misspelling depth, letter-cohort book size, and photo-finish peer. Not a difficulty grade.

Long-tail ranks near “triennial”

Sparse band: bars invert rank so rarer forms read shorter

corpus weight

What this shows Long-tail view: where “triennial” sits against similarly uncommon English ranks.

Source FrequencyWords open word-frequency list As of September 3, 2026
Key facts for triennial
PropertyValue
Headwordtriennial
LanguageEnglish
Part of speechAdjective
IPA/tɹaɪˈɛniəl/
Letters9
Frequency rank#53,921
Misspellings tracked0
Confusable pairs0
SourceWiktionary (kaikki.org)

Long-tail rank of “triennial” in English

Word frequency stretches from the small set of words we reach for constantly (left) out to the long tail barely used once in a while (right).triennialfalls in this rarity band:

#1#100#1K#10K#100K
← used constantlyrarely used →

The axis is logarithmic, with each marked tick roughly ten times rarer than the last. Rare peers in the same band: “tricolor” (#53,920), “trapdoor” (#53,919), “Trondheim” (#53,923). Among 3,151 “T” headwords, “triennial” is #53,921. Source: FrequencyWords open word-frequency list.

Rare enough to double-check

triennial is uncommon English at frequency #53,921 among 3,151 “T” headwords, classed as anadjective, transcribed /tɹaɪˈɛniəl/. Rarity is why readers land here mid-draft. 2 senses are on record.

Zero misspellings are on record for triennial in our index, typically a sign the spelling maps closely to how the word sounds. It is not paired with a close-neighbour confusable in our dataset, which typically means the spelling is too distinctive to be mistaken for another word.

Etymologically, the entry records: From Latin triennium (“three-year period”), from tres (“three”) + annus (“year”). By surface analysis, tri- + -ennial. The correct English form is triennial, spelled T-R-I-E-N-N-I-A-L.

Definition

  1. 1
    Happening every three years.
  2. 2
    Lasting for three years.

Recorded use

Wiktionary examples

These source excerpts show how triennial appears in context. They illustrate usage; the definition above remains the entry’s reference meaning.

  1. triennial elections
  2. They were constantly summoned to a triennial festival : and the most approved songs delivered at this assembly were ordered to be preserved in the custody of the king's historian or antiquary

Etymology

From Latin triennium (“three-year period”), from tres (“three”) + annus (“year”). By surface analysis, tri- + -ennial.

Synonyms

This word in other languages

Definitions, pronunciation, and etymology for this entry are drawn from Wiktionary via the kaikki.org structured extract (CC BY-SA); frequency ordering uses the FrequencyWords open word-frequency list (2018 English corpus, MIT). See the methodology for how each field is sourced and updated.

Frequently Asked Questions

How do you spell "triennial"?
"triennial" is spelled T-R-I-E-N-N-I-A-L. The IPA pronunciation is /tɹaɪˈɛniəl/.
What does "triennial" mean?
As an adjective, "triennial" means: Happening every three years.
How do you pronounce "triennial"?
The IPA (International Phonetic Alphabet) transcription for "triennial" is /tɹaɪˈɛniəl/. Click the speaker icon on the pronunciation badge above to hear it spoken aloud where audio is available.
What is the origin of the word "triennial"?
From Latin triennium (“three-year period”), from tres (“three”) + annus (“year”). By surface analysis, tri- + -ennial. See the full etymology section above for more details.
Is PlainSpell free to use?
Yes, PlainSpell is a completely free word reference. You can look up definitions, pronunciations, confusable pairs, homophones, and spelling corrections across 5 languages without any sign-up or subscription.

Similar English words by spelling shape

Same letter count and similar misspelling depth for "triennial", not the corpus desk frequency band.

Same letter count

Frequency-ranked English headwords with 9 letters (nearest by frequency rank).

Source: Wiktionary (via kaikki.org) Structured Wiktionary extract

Source: FrequencyWords open word-frequency list