Nefarious \Ne*fa"ri*ous\, a. [L. nefarius, fr. nefas crime, wrong; ne not + fas divine law; akin to fari to speak. See {No}, adv., and {Fate}.] Wicked in the extreme; abominable; iniquitous; atrociously villainous; execrable; detestably vile. [1913 Webster] Syn: Iniquitous; detestable; horrible; heinious; atrocious; infamous; impious. See {Iniquitous}. [1913 Webster] -- {Ne*fa"ri*ous*ly}, adv. -- {Ne*fa"ri*ous*ness}, n. [1913 Webster]