Etymograph

English

irregularity

Irregularity comes from Latin irrēgulāris ‘irregular, unusual’, from regō ‘to rule, govern’, and ultimately from Proto-Indo-European *h₃reǵ- ‘to straighten’.

  1. Proto-Indo-Europeanc. 4500–2500 BCE*h₃reǵ-1‘to straighten’reconstructed
  2. Proto-Indo-Europeanc. 4500–2500 BCE*h₃réǵeti1‘to straighten’reconstructed
  3. Proto-Italicc. 1500–700 BCE*regō1reconstructed
  4. Latinc. 75 BCE–200 CEregō2‘to rule, govern’
  5. Latinc. 75 BCE–200 CErēgula3
  6. Latinc. 75 BCE–200 CErēgulāris3
  7. Latinc. 75 BCE–200 CEirrēgulāris4‘irregular, unusual’
  8. Medieval Latinc. 600–1500irregularitas5
  9. Middle Frenchc. 1400–1600irrégularité5
  10. Englishearliest quotation 1959irregularity5

attested reconstructed ? uncertain or disputed deepest recorded ancestor

  1. 1 Wiktionary, Latin rego, which cites Rix
  2. 2 Wiktionary, Latin regula
  3. 3 Wiktionary, Latin irregularis
  4. 4 Wiktionary, Latin irregularitas
  5. 5 Wiktionary, English irregularity
  6. Earliest quotation in Wiktionary’s entry: 1959, Track-Recording Coach for B.R.: “A new track-recording vehicle has been developed for British…”.

Lineage

  1. Proto-Indo-Europeanc. 4500–2500 BCE*h₃reǵ-Wiktionary, Latin rego, which cites Rix‘to straighten’reconstructed
  2. Proto-Indo-Europeanc. 4500–2500 BCE*h₃réǵetiWiktionary, Latin rego, which cites Rix‘to straighten’reconstructed
  3. Proto-Italicc. 1500–700 BCE*regōWiktionary, Latin rego, which cites Rixreconstructed
  4. Latinc. 75 BCE–200 CEregōWiktionary, Latin regula‘to rule, govern’
  5. Latinc. 75 BCE–200 CErēgulaWiktionary, Latin irregularis
  6. Latinc. 75 BCE–200 CErēgulārisWiktionary, Latin irregularis
  7. Latinc. 75 BCE–200 CEirrēgulārisWiktionary, Latin irregularitas‘irregular, unusual’
  8. Medieval Latinc. 600–1500irregularitasWiktionary, English irregularity
  9. Middle Frenchc. 1400–1600irrégularitéWiktionary, English irregularity
  10. Englishearliest quotation 1959irregularityWiktionary, English irregularity. Earliest quotation in Wiktionary’s entry: 1959, Track-Recording Coach for B.R.: “A new track-recording vehicle has been developed for British…”

Linked words

through Proto-Indo-European *h₃reǵ- ‘to straighten’

right, real, royal, rich, correct, rank, roy, radar, arrangement, rack, rogue, arrange, rex, raj, interrogation, rake, dresser, rector, regal, rani, regency, undress, dressage, rajah, rhesus, derailleur, eldritch, riel, rectilinear, dirigible, retch, interregnum, 73 more

through Proto-Indo-European *h₃réǵeti ‘to straighten’

ana, anorexia, 40 more

through Proto-Italic *regō

regional, resource, directory, regiment, regimen, erectile, erectus, erector, 35 more

through Latin regō ‘to rule, govern’

source, director, address, region, direction, direct, dress, regime, realm, ruler, resurrection, erect, regent, rectify, insurrection, rectum, rectification, droit, incorrigible, dirge, recto, rectus, derecho, rectitude, regio, corregidor, 46 more

through Latin rēgula

rule, regulate, regula, 6 more

through Latin rēgulāris

regular, 2 more

Today it means

noun An instance of being irregular.

Sources

Sources: Wiktionary, “irregularity”; the older steps come from the Wiktionary entries for Latin rego, Latin regula, Latin irregularis, Latin irregularitas. 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 *h₃reǵ- / irregularity

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