insidious
Insidious (adjective) means causing harm slowly and quietly, so the danger isn't obvious until real damage is done. Example: “The disease is insidious, showing almost no symptoms until it has spread.”
How to use insidious
Learner’s notesIn plain EnglishSomething harmful that creeps up on you gradually rather than announcing itself.
Insidious describes gradual, hidden harm — it isn't simply a fancier word for "bad" or "evil."
Word forms
more insidious comparative, most insidious superlative
Fill the gap
Can you complete this real example?
The disease is _____, showing almost no symptoms until it has spread.
Etymology
From Latin insidiosus ("cunning, deceitful"), related to insidiae ("an ambush"), from insidere ("to sit in wait").
Rhymes for insidious
See all rhymes for insidious →Frequently asked questions
What does “insidious” mean?
The word “insidious” means causing harm slowly and quietly, so the danger isn't obvious until real damage is done. In plain terms, something harmful that creeps up on you gradually rather than announcing itself.
How do you pronounce “insidious”?
“Insidious” is pronounced ihn-SIH-dee-uhs (/ɪnˈsɪdi.əs/ in IPA).
How do you use “insidious” in a sentence?
Here is “insidious” used in a sentence: “The disease is insidious, showing almost no symptoms until it has spread.”
What part of speech is “insidious”?
“Insidious” is an adjective.
Where does the word “insidious” come from?
The word “insidious” comes from Latin. From Latin insidiosus ("cunning, deceitful"), related to insidiae ("an ambush"), from insidere ("to sit in wait").
Is “insidious” a common word?
“Insidious” is an uncommon word in modern English.
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