nefas

• nephās (Medieval Latin)

From ne (“not”) +‎ fās (“divine law”).

• (Classical Latin) IPA^(key): [ˈnɛ.faːs]
• (modern Italianate Ecclesiastical) IPA^(key): [ˈnɛː.fas]

nefās n sg (indeclinable, no genitive)

1. wrong; (moral) offense; wicked act; misdeed or misdoing
   • 29 BCE – 19 BCE, Virgil, Aeneid 2.585–586:

     “‘Extīnxisse nefās tamen et sūmpsisse merentīs / laudābor poenās [...].’”

     “‘Nevertheless, [for having] slain [such] an offender, and exacted [her] well-deserved punishments, I will be honored….’”
     (Aeneas in soliloquy speaks two perfect active infinitives – extinxisse and sumpsisse – as he considers whether to kill Helen.)

2. forbidden deed or act

Indeclinable noun (used only in the nominative and accusative), singular only.

• nefārius
• nefāstus

• “nefas”, in Charlton T. Lewis and Charles Short (1879) A Latin Dictionary, Oxford: Clarendon Press
• “nefas”, in Charlton T. Lewis (1891) An Elementary Latin Dictionary, New York: Harper & Brothers
• nefas in Gaffiot, Félix (1934) Dictionnaire illustré latin-français, Hachette.