Word
treacherous
Phoneticstreach·er·ous, stress on the first syllable
US/ˈtɹɛtʃɝəs/
UK/tɹˈɛtʃəɹəs/
Definition
adj. dangerous because of hidden risks or because you cannot trust someone. You use this to describe slippery roads or people who might betray you.
adj. characterised by hidden dangers or hazards; also describes a person who is guilty of deception or betrayal. Often used to describe environmental conditions like ice or currents.
Examples
“The mountain roads are treacherous during the winter.”
“The hikers decided to turn back because the narrow path along the cliff became too treacherous in the rain.”
“The protagonist must navigate a treacherous political landscape where today's allies could easily become tomorrow's enemies in the pursuit of power.”
Examples
simple
“The mountain roads are treacherous during the winter.”
contextual
“The hikers decided to turn back because the narrow path along the cliff became too treacherous in the rain.”
complex
“The protagonist must navigate a treacherous political landscape where today's allies could easily become tomorrow's enemies in the pursuit of power.”
Usage
Commonly used both literally for physical hazards and figuratively for social or political betrayal.
Real-World Examples
“Several trekkers and their guides say their journeys back down the mountains have been treacherous, taking up to three or four days and requiring them to pass collapsed roads and swept-away bridges.” “To reach Everest's summit Edmund Hillary and Tenzing Norgay had to climb sheer rock, while battling treacherous ice and a deadly lack of oxygen on the most dangerous part of the mountain.” “The Guardian investigation suggests a network of far-right Facebook groups has become an “engine of radicalisation”, and from them emerged an ecosystem where mainstream politicians are described as “treacherous”, “traitors” and “scum”.” “Since Roman times, it has been connected to both bleak moods and treacherous actions: the Roman scholar Quintilian defined “bad intention” as “something done … at night”.” Etymology
From Old French trecheros, tricheros (“deceitful”), equivalent to treacher + -ous. See treacher.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.
Word family
NOUN
ADJECTIVE
- Exam level
- CambridgeCambridgeCambridge English QualificationsThe exam suite from Cambridge University Press & Assessment, from A1 Movers up to C2 Proficiency. The benchmark names double as CEFR labels.B2 FirstIELTSIELTSInternational English Language Testing SystemThe 0–9 band test co-owned by the British Council, IDP, and Cambridge. Used for university entry, work, and migration.5.5–6.5TOEFL iBTTOEFL iBTTest of English as a Foreign Language, Internet-Based TestETS's academic English test, the standard route for US university admissions. Scored 0–120, with a 1–6 scale since 2026.1–6 scale: 4.0–4.572–94TOEICTOEICTest of English for International CommunicationETS's workplace English test, big in Japan and Korea. Listening & Reading scores 10–990 and tops out at C1.785–944
- Frequency
- Frequent
- Level
- B2 · Upper Intermediate
- Updated
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