adjective

pernicious

/pərˈnɪʃəs/ · say it: per·NISH·us

harmful in a gradual, hidden way

In From the Opinion Pages

In more detail

1. (adjective) harmful in a subtle or gradual way; causing serious damage without being easily noticed

2. (adjective) (of a disease) very dangerous and difficult to treat

Examples

1. The pernicious effects of social media on teenagers' mental health are becoming more apparent. 2. Pernicious anemia is a serious blood disorder that requires vitamin B12 treatment.

How to use pernicious

Pernicious describes harm that operates gradually and subtly, often undetected until serious damage is done. It carries a more literary and formal tone than simple 'harmful,' and is particularly common in medical contexts (pernicious anemia) and discussions of social or ideological damage. Unlike insidious, which emphasizes deception, pernicious emphasizes the progressive, cumulative nature of the damage.

Common phrases

pernicious habit
pernicious influence
pernicious anemia
pernicious effect
pernicious myth

Synonyms

insidious · harmful · dangerous · damaging · destructive

Opposites

beneficial · harmless · constructive

Word family

perniciousness (noun) · pernaciously (adverb)

A common mistake

Learners sometimes use pernicious to mean simply 'bad' or 'wrong' without the key implication of gradual, concealed harm that becomes serious over time.

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