The Collaborative International Dictionary
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.
Syn: Iniquitous; detestable; horrible; heinious; atrocious; infamous; impious. See Iniquitous. [1913 Webster] -- Ne*fa"ri*ous*ly, adv. -- Ne*fa"ri*ous*ness, n.
Wiktionary
adv. In a nefarious manner.
WordNet
adv. in a nefarious manner or to a nefarious degree; "nefariously involved in a conspiracy"
Usage examples of "nefariously".
The plots and falsehoods of this designing intriguer having been completely brought home to him, and it being made clear how nefariously he had deprived both his brothers and the British government of large tracts of territory, no time was lost in stripping him of his ill-gotten honours and estates, and reducing him to the rank of a simple chief.