Lewis & Short

nĕfans, antis, adj. [adjectival collat. form of ne-fas], impious, heinous (anteclass.): nefantia pro nefanda: Lucilius (Satyr. Lib. IV.): Tantalus qui poenas ob facta nefantia pendit, Non. 489, 14 sq.; Varr. Sat. Menip. 83, 4.