Etymograph

English

triennium

Triennium comes from Latin triennium ‘a period of three years, triennium’, from triennis ‘3-year’, and perhaps ultimately from Proto-Indo-European *h₂et- ‘to go’.

  1. Proto-Indo-Europeanc. 4500–2500 BCE*h₂et-1‘to go’uncertain
  2. Proto-Indo-Europeanc. 4500–2500 BCE*h₂ét-no-1reconstructed
  3. Proto-Italicc. 1500–700 BCE*atnos1‘year’uncertain
  4. Latinc. 75 BCE–200 CEannus2‘year’
  5. Latinc. 75 BCE–200 CEtriennis3‘3-year’
  6. Latinc. 75 BCE–200 CEtriennium3‘a period of three years, triennium’
  7. Englishtodaytriennium3

attested reconstructed ? uncertain or disputed deepest recorded ancestor

  1. 1 Wiktionary, Latin annus
  2. 2 Wiktionary, Latin triennis
  3. 3 Wiktionary, English triennium

Lineage

  1. Proto-Indo-Europeanc. 4500–2500 BCE*h₂et-Wiktionary, Latin annus‘to go’uncertain
  2. Proto-Indo-Europeanc. 4500–2500 BCE*h₂ét-no-Wiktionary, Latin annusreconstructed
  3. Proto-Italicc. 1500–700 BCE*atnosWiktionary, Latin annus‘year’uncertain
  4. Latinc. 75 BCE–200 CEannusWiktionary, Latin triennis‘year’
  5. Latinc. 75 BCE–200 CEtriennisWiktionary, English triennium‘3-year’
  6. Latinc. 75 BCE–200 CEtrienniumWiktionary, English triennium‘a period of three years, triennium’
  7. EnglishtodaytrienniumWiktionary, English triennium

Linked words

through Latin annus ‘year’

annual, ann, annuity, perennial, millennium, millennial, annum, biennial, biennale, 10 more

Today it means

noun A period of three years.

Sources

Sources: Wiktionary, “triennium”; the older steps come from the Wiktionary entries for Latin annus, Latin triennis. By Wiktionary contributors, CC BY-SA 4.0, via kaikki.org (dump of Oct 3 2026); text adapted and restructured. Language periods are conventional ranges, not dates for this word. License.

Etymograph / Proto-Indo-European *h₂et- / triennium

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