Treacherous
/ˈtrɛtʃərəs/
adjectiveB2
Definition
Treacherous means something or someone that can cause harm because it is unsafe or dishonest. It often describes places like roads or weather that look safe but are actually dangerous, or people who pretend to be friends but are not loyal.
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See It in Action
Dangerous because it is not safe or reliable
- •The mountain path was treacherous after the rain.
- •Driving in treacherous weather requires extra care.
- •The sea was treacherous with hidden rocks beneath the waves.
Not loyal or trustworthy; likely to betray
- •He was a treacherous friend who told secrets to others.
- •The spy was treacherous and worked for the enemy.
- •Be careful; treacherous people can hurt you when you least expect it.
Make It Stick
- ✓Think of "treacherous" like "dangerous" (A2 word), but with a secret risk that you might not see at first
- ✓Picture walking on ice that looks solid but suddenly breaks—this surprise danger is treacherous
- ✓It's the feeling when you trust someone, but they do something bad behind your back
- ✓Sounds like "TREACH-er-ous" → imagine a "treach" (like "trap") that hides danger waiting to hurt you
- ✓Think of stories where a friend suddenly betrays the hero—this is a treacherous act
- ✓NOT like "dangerous" which can be very clear and visible; treacherous danger is often hidden or unexpected
- ✓NOT like "risky" which means chance of harm; treacherous means harm is likely and often sneaky
- ✓NOT like "safe" which means no danger at all
Try Other Words
- •Dangerous: likely to cause harm or injury (Use when the danger is clear and visible)
- •Untrustworthy: not able to be trusted (Use when talking about people who betray or lie)
- •Risky: involving a chance of harm or loss (Use when danger is possible but not certain)
- •Deceptive: misleading or tricking someone (Use when something looks safe but is not)
Unboxing
- •Prefix: "treach-" from Old French "trecher" meaning to cheat or betray
- •Root: related to "treason," which means betrayal of trust or loyalty
- •Suffix: "-erous" meaning full of or having the quality of
- •Origin: Comes from Old French and Latin, related to the idea of betrayal and danger
- •Historical use: Originally used to describe people who betray; later also used for dangerous places or things that can cause harm unexpectedly
- •Modern use: Describes both physical dangers (like roads, weather) and personal dangers (like untrustworthy people)
Reflect & Connect
•Can something be physically safe but still feel treacherous? Why or why not?
•How does knowing a person is treacherous change the way you act around them?
Fill in the blanks
1.The mountain trail was treacherous because the rain made the rocks ___ and slippery.
2.A treacherous friend might ___ your secrets to others without warning.
3.Unlike obvious danger, treacherous conditions often ___ hidden risks that surprise people.
4.When the weather is treacherous, drivers must ___ their speed and be very careful.
5.The spy’s treacherous actions showed he was not ___ to his country.
6.Treacherous roads are especially dangerous when you cannot ___ where the danger is.
7.People say the ocean is treacherous because of ___ currents and hidden rocks.