Meaning of “treacherous” - Learner’s Dictionary

treacherous

adjective us uk /ˈtretʃərəs/
DANGEROUS

very dangerous, especially because of bad weather conditions:

Ice had made the roads treacherous.
NOT LOYAL formal

If someone is treacherous, they deceive people who trust them.

(Definition of “treacherous” from the Cambridge Learner’s Dictionary © Cambridge University Press)