Insidious
/ɪnˈsɪdiəs/
adjectiveC1
Definition
Insidious means something dangerous or harmful that grows or develops quietly and secretly. It is often used to describe problems, diseases, or situations that get worse little by little without people realizing it until it is too late.
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See It in Action
Harmful in a slow and secret way
- •The insidious disease spread without symptoms at first.
- •Insidious lies can destroy trust over time.
- •Pollution is an insidious problem that slowly damages the environment.
Dangerous because it is not noticed quickly
- •The insidious effects of stress can harm your health.
- •Insidious advertising can influence people without them realizing it.
Make It Stick
- ✓Think of "insidious" like "bad," but not loud or obvious—it's quiet and hidden, like a secret problem
- ✓Imagine a small crack in a wall that slowly gets bigger over time, but you don’t see it at first
- ✓It’s the feeling when something bad happens slowly and surprises you later, like a slow trick or trap
- ✓Sounds like "in-SID-ee-us" → imagine a secret "side" door where danger quietly enters without being seen
- ✓Think of stories where a villain works quietly, slowly causing trouble without anyone knowing
- ✓NOT like "dangerous" (which is often clear and visible), insidious danger is hidden and grows slowly
- ✓NOT like "sudden" harm, insidious harm happens little by little over time
- ✓NOT like "obvious problem," insidious problems are hidden or disguised, making them harder to notice
Try Other Words
- •Hidden: not seen or noticed (Use when the danger or problem is not visible but not necessarily harmful)
- •Gradual: happening slowly over time (Use when focusing on slow development, not necessarily harmful)
- •Dangerous: likely to cause harm or injury (Use when harm is clear and immediate, not secret or slow)
- •Secret: kept from others (Use when emphasizing the hidden nature without the harmful part)
Unboxing
- •Word parts: "in-" (prefix meaning "in" or "on") + "sidious" (from Latin "insidiae" meaning "ambush" or "trap")
- •Etymology: From Latin "insidiosus," meaning "full of ambushes" or "treacherous"
- •Historical development: Originally used to describe traps or ambushes that are hidden and dangerous; later extended to describe slow and hidden dangers
- •Modern usage: Used to describe problems, diseases, or behaviors that are harmful and develop quietly without being noticed at first
Reflect & Connect
•Can you think of a situation in your life where something insidious caused problems slowly without you noticing?
•Why do you think it is important to recognize insidious dangers early, even if they seem small or hidden?
Fill in the blanks
1.The insidious disease ___ symptoms at first, making it hard to detect early.
2.Stress can have insidious effects on health because it builds up ___ over time.
3.Unlike sudden danger, insidious problems grow ___ and quietly.
4.When someone spreads insidious rumors, they do it ___ to harm others without being noticed.
5.Insidious threats often go ___ until the damage is serious.
6.People should be careful about insidious influences that can ___ their decisions without them realizing.
7.The insidious nature of the problem means it requires ___ attention to catch early.