Etymograph

English

rigorous

Rigorous comes from Late Latin rigōrōsus, and goes back to Proto-Indo-European *Hreyǵ-.

  1. Proto-Indo-Europeanc. 4500–2500 BCE*Hreyǵ-1root named by Wiktionary
  2. Late Latinc. 200–600 CErigōrōsus1
  3. Anglo-Normanc. 1066–1400rigoreus1
  4. Middle Englishc. 1150–1500rigorous1
  5. Englishearliest quotation 1946rigorous1

attested reconstructed ? uncertain or disputed deepest recorded ancestor

  1. 1 Wiktionary, English rigorous
  2. Earliest quotation in Wiktionary’s entry: 1946, and December, George Westinghouse, 1846-1914: “From this time onwards, the Westinghouse air brake literally…”.

Lineage

  1. Proto-Indo-Europeanc. 4500–2500 BCE*Hreyǵ-Wiktionary, English rigorousroot named by Wiktionary
  2. Late Latinc. 200–600 CErigōrōsusWiktionary, English rigorous
  3. Anglo-Normanc. 1066–1400rigoreusWiktionary, English rigorous
  4. Middle Englishc. 1150–1500rigorousWiktionary, English rigorous
  5. Englishearliest quotation 1946rigorousWiktionary, English rigorous. Earliest quotation in Wiktionary’s entry: 1946, and December, George Westinghouse, 1846-1914: “From this time onwards, the Westinghouse air brake literally…”

Equivalent to rigor + -ous

Proto-Italic *rigā- ‘to lead toward’

Latin rigō ‘to be rigid’

Latin rigor ‘stiffness, rigidity, rigor, cold, harshness’

English rigor

Linked words

through Proto-Indo-European *Hreyǵ-

reach, irrigation, rigid, rigour, 8 more

Today it means

adj Showing, causing, or favoring rigour/rigor; scrupulously accurate or strict; thorough.

Sources

Sources: Wiktionary, “rigorous”. 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 *Hreyǵ- / rigorous

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