From Longman Dictionary of Contemporary Englishtreacheroustreach‧e‧rous /ˈtretʃərəs/ adjective 1 UNFAITHFULsomeone 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 leader2 DANGEROUSground, 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.► see thesaurus at dangerous —treacherously adverb
Examples from the Corpus
treacherous• I was uncomfortable around boys, and undressing with them seemed not only bizarre but treacherous.• I have tried to explain that in Claudia's case memory is particularly treacherous, but Letterman likes the idea of ambiguity.• They traveled on horseback over treacherous Himalayan footpaths.• Strong winds and heavy rain are making driving conditions treacherous in some areas.• The land he rode was marshy, forcing him to weave an intricate course past the more treacherous patches.• Her stepmother was a treacherous, selfish woman.• The speed of light is a treacherous thing.• There are treacherous underwater currents along this stretch of coast.• They are steep and treacherous with outcropping rock.• He knew he had been betrayed by a scheming and treacherous woman. 