Etymologically

fas

Etymology and origin of the Latin word fas

Confidence
Probable
Formation
Inherited
First attested
Naevius
Inherited from
Proto-Italic *fās
Ultimate origin
Proto-Indo-European (*bʰeh₂-)

Pronunciation

  • IPA (Classical): [ˈfaːs][1]
  • IPA (Ecclesiastical): [ˈfas][1]

Forms

fās n sg (indeclinable, no genitive)[1]

Etymology

It is inherited from Proto-Italic *fās, probably inherited from Proto-Indo-European *bʰéh₂-os (“saying, utterance”), from the root Proto-Indo-European *bʰeh₂- (“to speak”) of fārī.[2][1] De Vaan thinks the noun first survived only in the phrase “the saying exists”, hence “it is right”, and that fāstus and fānum were derived from it.[2] The OLD calls the connection with fārī doubtful.[3]

Earliest recorded meaning

De Vaan dates it from Naevius.[2] Köbler dates Naevius c. 235–200 BC.[4]

Semantic evolution

It was what is right or permitted by divine law, the will of heaven, and then what is morally right or proper.[3] It was usually a predicate, fās est “it is right, it is allowed”, and was often opposed to nefās.[3] Cicero speaks of destroying all iūs ac fās, human and divine law.[5] Isidore defines it as divine law, against iūs, human law: to cross another's field is fās, but not iūs.[6]

Medieval Latin kept it in the phrase contrā iūs fāsque.[7] Its negative nefās gave nefārius, the source of English nefarious about 1600.[8]

Timeline

  • c. 235–200 BC – Naevius uses it.[2][4]
  • 81–43 BC – Cicero speaks of destroying all iūs ac fās.[5][4]
  • c. 560–636 AD – Isidore contrasts fās with iūs.[6][4]
  • c. 1600 – English nefarious is recorded.[8]

Meanings

Noun

  1. What is right by divine law.[3]
  2. The will of heaven.[3]
  3. What is morally right, proper, fās est, it is allowed.[3]
  4. A sense of right; a right, a claim.[3]

Word family

  • for
  • English nefarious

Usage notes

It is indeclinable and used almost only in the nominative and accusative.[3][1]

References

  1. ^ a b c d e Wiktionary, the free dictionary, https://en.wiktionary.org
  2. ^ a b c d de Vaan, Michiel (2008), Etymological Dictionary of Latin and the other Italic Languages, Leiden Indo-European Etymological Dictionary Series 7, Leiden; Boston: Brill
  3. ^ a b c d e f g h Glare, P. G. W., ed. (2012), Oxford Latin Dictionary, 2nd ed., Oxford: Oxford University Press
  4. ^ a b c d Köbler, Gerhard (2010), Lateinisches Abkunfts- und Wirkungswörterbuch für Altertum und Mittelalter, online ed., koeblergerhard.de
  5. ^ a b Gaffiot, Félix (2016), Dictionnaire latin-français, new ed. by Gérard Gréco et al. (Gaffiot 2016), online ed.
  6. ^ a b Isidore of Seville, Etymologiarum sive Originum libri XX, ed. W. M. Lindsay (Oxford, 1911).
  7. ^ Latham, R. E., D. R. Howlett, R. K. Ashdowne, et al. (1975–2013), Dictionary of Medieval Latin from British Sources, London: British Academy / Oxford University Press
  8. ^ a b Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com

Related etymologies

  • ovum · also from Proto-Indo-European
  • oculus · also from Proto-Indo-European
  • navis · also from Proto-Indo-European
  • mirus · also from Proto-Indo-European
  • laxus · also from Proto-Indo-European
  • lateo · also from Proto-Indo-European
  • gravis · also from Proto-Indo-European
  • tenuis · also from Proto-Indo-European
Cite this entry

“Fas.” Etymologically, 16 Oct. 2026, etymologically.com/la/fas. Accessed 16 Oct. 2026.

Last edited on . ·