on one's guard
Alert for danger
On one's guard means alert and watchful, ready to defend against danger or deception: Stay on your guard around him—he's not to be trusted.
The phrase comes from fencing and military readiness, where being on guard means holding a defensive position.
To put someone on their guard is to warn them; to catch someone off guard is to surprise them when they're unprepared.
- cautiousnessCareful, watchful disposition
- self-defenseProtecting oneself from harm
- defense mechanismUnconscious self-protective mental process
- alertnessActive mental awareness
- stay alertMaintain active awareness
keep watch · vigilance · on the lookout · prudence · play it safe · watchfulness · heedfulness · perceptiveness · distrustfulness · trust issues · red flag · circumspection · skepticism · attentiveness · suspicion · wariness · watch your back · foresight
on one's guardoff guard
Not prepared for something
unguarded · unwary · inattentive · careless · oblivious
on one's guardat ease
Relaxed, not tense
relaxed · laid-back · carefree · untroubled · nonchalant
ones, guard, guards, guarded, guarding, guardedly, guardian, guardians, guardianship