- Sinful, villainous, criminal, or wicked, especially when noteworthy or notorious for such characteristics.
- Synonyms: evil, iniquitous, sinister, underhanded, vile, good-for-nothing, Thesaurus:evil
- 1828, James Fenimore Cooper, The Red Rover, ch. 2:
- "If the vessel be no fair-trading slaver, nor a common cruiser of his Majesty, it is as tangible as the best man's reasoning, that she may be neither more nor less than the ship of that nefarious pirate the Red Rover."
- 1877, Anthony Trollope, The Life of Cicero, ch. 9:
- Mommsen . . . declares that Catiline in particular was "one of the most nefarious men in that nefarious age. His villanies belong to the criminal records, not to history."
- 1921, P. G. Wodehouse, The Indiscretions of Archie, ch. 26:
- The fact that the room was still in darkness made it obvious that something nefarious was afoot. Plainly there was dirty work in preparation at the cross-roads.
- 2009 Oct. 14, Monica Davey, "Fact Checker Finds Falsehoods in Remarks ↗," New York Times (retrieved 12 May 2014):
- “I try to let everyone back here in Minnesota know exactly the nefarious activities that are taking place in Washington.”
- Vikings, pirates, outlaws, Native Americans, Confederate soldiers, Roman soldiers, hessians, and German soldiers in both world wars all committed many nefarious deeds.
- Aliens have a nefarious connotation in many science fiction books.
- French: infâme, scandaleux, criminel
- German: berüchtigt, schändlich, ruchlos, verachtenswert, bösartig, böse
- Italian: nefasto, scellerato, diabolico, infernale, sinistro
- Portuguese: nefasto
- Russian: бесче́стный
- Spanish: nefario, nefando, feo, infame, vicioso, malvado, inicuo