Etymograph

English

bissext

Bissext comes from Latin bisextus ‘intercalary day’, from sextus ‘sixth’, and ultimately from Proto-Indo-European *dwóh₁ ‘two’.

  1. Proto-Indo-Europeanc. 4500–2500 BCE*dwóh₁1‘two’reconstructed
  2. Proto-Indo-Europeanc. 4500–2500 BCE*dwís1‘twice, doubly’reconstructed
  3. Proto-Italicc. 1500–700 BCE*dwis1‘twice’reconstructed
  4. Old Latinc. 700–75 BCEduis1
  5. Latinc. 75 BCE–200 CEbis1‘twice, two times, on two occasions, in two ways’
  6. Latinc. 75 BCE–200 CEsextus1‘sixth’
  7. Latinc. 75 BCE–200 CEbisextus2‘intercalary day’
  8. Middle Englishc. 1150–1500bisext2
  9. Englishtodaybissext2

attested reconstructed ? uncertain or disputed deepest recorded ancestor

  1. 1 Wiktionary, Latin bisextus
  2. 2 Wiktionary, English bissext

Lineage

  1. Proto-Indo-Europeanc. 4500–2500 BCE*dwóh₁Wiktionary, Latin bisextus‘two’reconstructed
  2. Proto-Indo-Europeanc. 4500–2500 BCE*dwísWiktionary, Latin bisextus‘twice, doubly’reconstructed
  3. Proto-Italicc. 1500–700 BCE*dwisWiktionary, Latin bisextus‘twice’reconstructed
  4. Old Latinc. 700–75 BCEduisWiktionary, Latin bisextus
  5. Latinc. 75 BCE–200 CEbisWiktionary, Latin bisextus‘twice, two times, on two occasions, in two ways’
  6. Latinc. 75 BCE–200 CEsextusWiktionary, Latin bisextus‘sixth’
  7. Latinc. 75 BCE–200 CEbisextusWiktionary, English bissext‘intercalary day’
  8. Middle Englishc. 1150–1500bisextWiktionary, English bissext
  9. EnglishtodaybissextWiktionary, English bissext

Linked words

through Proto-Indo-European *dwóh₁ ‘two’

two, doubt, vice, twin, dual, duo, vicious, duet, twain, dubious, disparate, twig, deuce, bes, 20 more

through Proto-Indo-European *dwís ‘twice, doubly’

defeat, diplomacy, betwixt, 11 more

through Proto-Italic *dwis ‘twice’

binary, binocular, 4 more

through Latin bis ‘twice, two times, on two occasions, in two ways’

biceps, bis, 3 more

Today it means

noun The bissextile intercalary day.

Sources

Sources: Wiktionary, “bissext”; the older steps come from the Wiktionary entry for Latin bisextus. 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 *dwóh₁ / bissext

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