Meaning & use
insidiously
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Meanings
adverbnot comparableformal
In a way that is slow, hidden, and harmful, so that damage is done before it is noticed.
Grammar: Modifies a verb or adjective, usually about something harmful: spread insidiously.
Patterns
- spread insidiously
- insidiously harmful
The disease spread insidiously through the village.
Doubt crept insidiously into his mind.
The rumor insidiously damaged her reputation.
adverbnot comparableliterary
In a sly, deceitful way that traps or tricks someone.
Grammar: Describes secret plotting or manipulation.
Patterns
- act insidiously
- work insidiously
He insidiously turned the committee against her.
The salesman insidiously flattered the customers.
The plan worked insidiously, one small favor at a time.
Common combinations
- spread insidiously
- Fear spread insidiously through the town.
- insidiously creep
- Rust can insidiously creep under the paint.
- insidiously harmful
- Some habits are insidiously harmful.
- work insidiously
- Propaganda can work insidiously over many years.
- insidiously subtle
- The change was insidiously subtle.
Synonyms and how they differ
- stealthily
- Stealthily means quietly and secretly, but does not always imply harm the way insidiously does.
- treacherously
- Treacherously suggests betrayal or hidden danger, which is not always gradual.
- subtly
- Subtly is neutral and means in a fine, hard-to-notice way, with no harm implied.
- furtively
- Furtively describes sneaky, secretive behavior in a moment, not a gradual harm.
Opposites
Word family
- insidious adjective
- gradual and harmful without being noticed
- insidiousness noun
- the quality of being insidious
Commonly confused: insidiously or invidious? insidiously or insipid?
insidiously vs invidious
Invidious means likely to cause resentment or seem unfair, as in an invidious comparison, which differs from insidious, meaning slowly harmful.
insidiously vs insipid
Insipid means dull or tasteless, and is unrelated to hidden harm.
Practice
Which sentence uses insidiously correctly?
Choose one answer.
Insidiously describes slow, hidden harm, like mold spreading unseen. The other sentences describe pleasant or neutral things.
Make it your own
Write a sentence using “insidiously”, then check it and compare it with the examples above.