Meaning & use
pernicious
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Meanings
adjectivecomparable
Causing serious harm in a slow, quiet way that is hard to notice at first.
Grammar: Used before a noun (a pernicious effect) or after a linking verb (the effect is pernicious).
Patterns
- pernicious effect
- pernicious influence
- pernicious to something
The new law had a pernicious effect on small businesses, slowly driving many of them to close.
Rumors can be pernicious, spreading quietly until they damage a person's reputation.
They warned that the pernicious influence of organized crime was growing in the region.
adjectivenot comparablemedical
(medical) Causing severe illness, especially pernicious anemia, a condition where the body cannot absorb enough vitamin B12.
Grammar: Used mainly in the fixed phrase pernicious anemia; not usually used in the comparative form.
Patterns
- pernicious anemia
She was diagnosed with pernicious anemia and needed regular vitamin B12 injections.
Pernicious anemia can cause tiredness and nerve damage if left untreated.
Word forms
| comparative | more pernicious |
|---|---|
| superlative | most pernicious |
Common combinations
- pernicious effect
- The pernicious effect of the policy was not seen for years.
- pernicious influence
- They tried to limit the pernicious influence of violent video games on children.
- pernicious myth
- It is a pernicious myth that people can become rich simply by working harder.
- pernicious to
- Such gossip is pernicious to the trust within a team.
Synonyms and how they differ
- harmful
- Harmful is the general word for anything that causes damage, while pernicious emphasizes harm that happens slowly and is hard to notice.
- insidious
- Insidious is very close, but it often suggests something that spreads secretly and is more deceitful, whereas pernicious just means destructive.
- destructive
- Destructive suggests obvious and often violent damage, while pernicious damage is gradual and quiet.
Opposites
Word family
- perniciously adverb
- In a pernicious manner; causing harm gradually.
- perniciousness noun
- The quality of being pernicious; the state of causing slow harm.
Commonly confused: pernicious or pernicious vs. Pernickety? pernicious or pernicious vs. Pernicious anemia?
pernicious vs pernicious vs. Pernickety
Pernickety means overly fussy about details, while pernicious means harmful. They sound somewhat similar but have completely different meanings.
pernicious vs pernicious vs. Pernicious anemia
The medical sense is a specific condition, not just any harmful situation. Do not use 'pernicious' alone to mean 'anemic'.
Practice
The new policy had a ______ effect on the community, slowly eroding trust over many years.
Choose one answer.
Pernicious means causing slow, hidden harm, which fits the idea of eroding trust gradually. Pernickety means fussy about details, permissible means allowed, and perceptive means quick to notice things—none fit the harmful, gradual effect described.
Make it your own
Write a sentence using “pernicious”, then check it and compare it with the examples above.