on (one's) guard

(redirected from on their guard)

on (one's) guard

Especially careful or vigilant; prepared for danger or surprises. He's got a lot of tricky moves, so be on your guard! Those trails can be a bit treacherous to climb; I just hope she's on her guard.
See also: guard, on

*on (one's) guard (against someone or something)

alert against someone or something. (*Typically: be ~; keep ~; remain ~; stay ~.) Try to stay on guard against pickpockets. I am always on my guard. Be on guard when you go into the city.
See also: guard, on

on one's guard

see under off guard.
See also: guard, on

on your guard

or

on guard

COMMON If you are on your guard or on guard, you are prepared to protect yourself against trouble. Note: Your guard is the position that you get in when you are ready to defend yourself in sports such as boxing or fencing. When Hilton came, he would have to be on his guard each second, for the man was dangerous. A journalist asked a question about his private life and instantly, the footballer was on guard. Compare with off your guard.
See also: guard, on

on (one's) guard

Alert and watchful; cautious.
See also: guard, on