Definition of “be on (your) guard” - English Dictionary

british dictionary

“be on (your) guard” in British English

See all translations

be on (your) guard

C2 to be careful to avoid being tricked or getting into a dangerous situation:

You always have to be on your guard against pickpockets.

(Definition of “be on (your) guard” from the Cambridge Advanced Learner's Dictionary & Thesaurus © Cambridge University Press)