1 someone who is treacherous cannot be trusted because they are not loyal and secretly intend to harm you:
a sly and treacherous woman
a treacherous plot to overthrow the leader
2 ground, roads, weather conditions etc that are treacherous are particularly dangerous because you cannot see the dangers very easily:
treacherous mountain roads
Strong winds and loose rocks made climbing treacherous.
treacherously adverb
WORD FOCUS: dangerous WORD FOCUS: dangerous
similar words: hazardous, risky, treacherous, perilous literary

See also

Dictionary results for "treacherous"
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