ENGLISH
REFERENCE

nefarious

adj.
C1 Advanced US //nəˈfɛɹiəs// UK //nəfˈeəɹɪəs// ne·far·i·ous

adj. describing something that is very bad, dishonest, or illegal. You use this to talk about activities that people do to hurt others or break the law.

adj. describing actions or intentions that are wicked, dishonest, or illegal. Often used to describe organized crime or secret plots.


SIMPLE

The group was involved in nefarious activities.

CONTEXTUAL

The detective spent months investigating the nefarious dealings of the local gang.

COMPLEX

The novel explores the nefarious influence of corporate lobbying on the democratic process, suggesting that the pursuit of profit often overrides the public good.

Synonyms
Origin

From Latin nefārius (“execrable, abominable”), from nefās (“something contrary to divine law, an impious deed, sin, crime”), from ne- (“not”) + fās (“the dictates of religion, divine law”), which is related to Latin for (“to speak, to say”) and cognate to Ancient Greek φημί (phēmí, “to say”).

© 2026 English Reference