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Etymology and origin of the French word rein

Confidence
Established
Formation
Inherited
First attested
c. 1120 Cambridge Psalter More words from the 12th century
Inherited from
Latin ren via Old French
Ultimate origin
Latin rēn
Etymology tree
inherited borrowed derived
Latin rēn
French rein
From the same root
Latin rēnālis ← rēn

Pronunciation

Forms

rein m (plural reins)[1] Old French reins, rains (plural), Middle French singular rain.[2][3][4]

Etymology

It is inherited from Old French reins, inherited from Latin rēnēs (“kidneys, loins”), a word used almost only in the plural.[3][5][6] In Christian Latin the plural also meant the loins as the seat of the feelings, and the back.[3][5] Rey calls the Latin word of unknown origin.[5]

Only the plural belonged to the popular language.[6] The singular for the organ is found once in a 14th-century medical text, then from 1538, and was probably taken again from medical Latin.[6][5]

Cognate with Italian rene, Occitan ren, Portuguese rim and Old Spanish rene.[7][2]

Earliest recorded meaning

The plural is first recorded in the first half of the 12th century in the Cambridge Psalter, for the lumbar region and, as in the Bible, the seat of the hidden feelings.[3][5] A 12th-century Book of Kings describes a man with a belt of skins entur les reins “around his loins”.[2]

Semantic evolution

The plural kept the sense “lower back” and gave many phrases: avoir les reins forts (1660), later avoir les reins solides (1904), for someone able to bear a heavy load, tour de reins (1870) and coup de reins (1891, Huysmans).[5] The biblical pairing of the kidneys, seat of the passions, with the heart gave sonder les reins et les cœurs.[5] Être faible de reins “to be unable” is in Marot (1531).[3]

The singular, for the organ that makes urine, is recorded as rains in 1328 and as rein in 1538 in Robert Estienne.[3][8] By analogy the word named the haunches of a vault in building (1491).[3][5] Modern medicine added rein flottant (1949) and rein artificiel (1964).[5]

Timeline

  • c. 1120 – The plural appears in the Cambridge Psalter.[3][5]
  • 1328 – Rains is used of the kidney.[3]
  • 1491 – Faux rains in building.[3]
  • 1531 – Marot writes foible de reins “too weak”.[3]
  • 1538 – Robert Estienne records the singular rein.[8][4]
  • 1660 – Avoir les reins forts is recorded.[5]
  • 1690 – The derived verb éreinter appears.[6][5]
  • 1870 – Tour de reins is recorded.[5]
  • 1964 – Rein artificiel is recorded.[5][8]

Meanings

Noun

  1. (anatomy) A kidney: On lui a greffé un rein.[9][3]
  2. (in the plural) The lower back, the loins: avoir mal aux reins, une chute de reins, un tour de reins.[9][1]
  3. Avoir les reins solides: to be strong enough to bear a burden, or rich enough to survive a blow.[9][5]
  4. (architecture) The haunch of a vault, the part between the springing and the crown.[3][8]
  5. Rein artificiel: a dialysis machine, and rein flottant, a kidney that has slipped from its place.[8][5]

Word family

  • éreinter
  • éreintement
  • rénal
  • rognon
  • Latin rēn

Usage notes

Littré also lists rein as another spelling of rain, a forestry word for the edge of a wood,[2] which the TLFi derives from Frankish *rain “border”.[3]

References

  1. ^ a b c Wiktionary, the free dictionary, https://en.wiktionary.org
  2. ^ a b c d Littré, Émile (1873–1877), Dictionnaire de la langue française, 4 vols. and supplement, Paris: Hachette
  3. ^ a b c d e f g h i j k l m n Trésor de la langue française informatisé (2004), ATILF – CNRS & Université de Lorraine, atilf.fr/tlfi; electronic version of Imbs, Paul; Quemada, Bernard, eds. (1971–1994), Trésor de la langue française, Paris: CNRS / Gallimard
  4. ^ a b Rey, Alain, ed. (2005), Le Grand Robert de la langue française, electronic version, Paris: Le Robert
  5. ^ a b c d e f g h i j k l m n o p Rey, Alain, ed. (1992), Dictionnaire historique de la langue française, Paris: Le Robert
  6. ^ a b c d Bloch, Oscar; Wartburg, Walther von (1989), Dictionnaire étymologique de la langue française, 8th ed., Paris: Presses universitaires de France
  7. ^ Meyer-Lübke, Wilhelm (1935), Romanisches etymologisches Wörterbuch, 3rd ed., Heidelberg: Winter
  8. ^ a b c d e Guilbert, Louis; Lagane, René; Niobey, Georges, eds. (1971–1978; 1989), Grand Larousse de la langue française, Paris: Larousse
  9. ^ a b c Rey-Debove, Josette; Rey, Alain, eds. (2007), Le Petit Robert de la langue française, Paris: Le Robert

Related etymologies

Cite this entry

“Rein.” Etymologically, 11 Nov. 2026, etymologically.com/fr/rein. Accessed 12 Nov. 2026.

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