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The Complete Vocabulary Builder Workbook



How to pronounce insidious (audio)

Dictionary definition of insidious

Harmful or dangerous in a subtle or gradual way, rather than being obvious or immediate.
"The insidious corruption within the organization was eventually exposed."

Detailed meaning of insidious

It can refer to an action or a plan that is intended to trap or deceive someone and it can also refer to an illness that progresses slowly and undetectably. The term also used to describe behavior that is sneaky and underhanded, as well as to describe a person who is deceitful or treacherous.

In general, something that is insidious is not to be trusted and should be approached with caution, as it may have hidden or long-term negative effects.

Example sentences containing insidious

1. The insidious effects of air pollution on health are often underestimated.
2. The insidious spread of misinformation on social media can cause harm to society.
3. He fell victim to the insidious whispers of jealousy and resentment.
4. The novel depicts the insidious nature of systemic racism in society.
5. Insidious discrimination still exists in many workplaces, often unnoticed by those not affected.
6. The drug had insidious side effects that only showed up years after treatment.

History and etymology of insidious

The adjective 'insidious' has its roots in Latin, originating from the word 'insidiosus,' which means 'cunning' or 'treacherous.' This Latin term is derived from 'insidiae,' which refers to 'ambushes' or 'traps.' The word 'insidiae' itself has connections to 'insidere,' meaning 'to sit in' or 'to lie in wait.' Therefore, 'insidious' carries the etymological idea of something lying in wait or working secretly to deceive or harm. In its modern usage, 'insidious' describes things that are harmful or dangerous in a subtle or gradual way, often not immediately apparent but eventually causing harm, mirroring the treacherous and deceptive nature that its Latin origin conveys.

Quiz: Find the meaning of insidious

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Further usage examples of insidious

1. The insidious erosion of privacy rights is a matter of great concern.
2. He was unaware of the insidious damage being done to his reputation.
3. The insidious decline in the quality of education worried the parents.
4. The insidious influence of certain television programs can impact children's behavior.
5. Stress can have insidious effects on our mental and physical health.
6. The insidious infiltration of the malware caused the entire network to collapse.
7. She couldn't perceive the insidious changes that the illness brought about.
8. The insidious growth of the tumor remained unnoticed for years.
9. The insidious spread of the invasive species disrupted the ecosystem.
10. The insidious undermining of her confidence by her peers led to her isolation.
11. The insidious disease gradually stripped him of his vitality.
12. The insidious encroachment of the desert threatened the small farming community.
13. The insidious nature of addiction makes it difficult to overcome.
14. The insidious nature of the virus made it challenging to detect and contain.
15. Insidious rumors began to undermine the team's unity slowly.
16. An insidious addiction can quietly consume one's life.
17. The insidious effects of pollution on health are often underestimated.
18. In an insidious manner, doubt crept into their once-solid friendship.
19. The insidious decline in the economy went unnoticed by many.
20. An insidious ideology can slowly erode a society's values.
21. The insidious spread of misinformation can be highly destructive.
22. Insidious habits can have a long-lasting impact on personal well-being.
23. The insidious manipulation of public opinion is a growing concern.
24. Insidious stress can take a toll on mental and physical health over time.



stealthy, overt, harmless, benign


Illusion and Insincerity, Fear and Ferocity, Duplicity and Deceit, Harmful and Detrimental

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