Added 10 October 2026 nefariously adverb Categories: Describing WordsObscure Words adverb ! Definition from Wiktionary (CC BY-SA). More about nefariously at Wordnik → Where our words come from → In a nefarious manner. Related Words: sinisterlydeviouslyfiendishlymalignlyfraudfullydiabolicallydevilishlycriminouslymischievouslyfraudulentlywickedlyperversely Back to today's word