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English definition of “treacherous”

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treacherous

adjective  /ˈtretʃ·ər·əs/ us  

treacherous adjective (DANGEROUS)

(of the ground or the sea) extremely dangerous, esp. because of bad weather conditions: Freezing rain made driving treacherous.

treacherous adjective (NOT LOYAL)

(of a person) guilty of deceiving someone who trusts you: He was treacherous, or at least sneaky.
(Definition of treacherous from the Cambridge Academic Content Dictionary © Cambridge University Press)
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