armed, uniformed
The building is protected by armed guards.

border, gate (AmE), prison, security
head
personal, private
military

post, station
Guards had been posted all around the TV studio.

patrol sth
Guards patrolled the perimeter fence.

protect sth
escort sb
be on duty

duty
dog

close
24-hour, constant, round-the-clock
armed
The accused was taken to court under armed guard.

heavy
He arrived under heavy guard.

military, police

off (your) guard
The question seemed to catch him off his guard.
He caught me completely off guard.

on (your) guard
Several police officers were on guard outside the factory.
He was always on his guard against moneymaking schemes.

under guard
The prisoners were under close guard.

guard against, guard over
Two police officers kept guard over the burned-out building.

drop your guard
Matt relaxed a little, dropping his guard.

keep guard of sth
Would you like me to keep guard of your room?

keep your guard up, keep up your guard
No one can keep their guard up all the time.

stand guard
A solider stood guard outside the palace.

civil, national, palace, presidential, royal
honour/honor
advance
elite

change
The guard was changed every two hours.

call out
It would only be a matter of minutes before the alarm was raised and the guard called out.

guard of honour/honor
Fellow soldiers formed a guard of honour/honor at his wedding.

trigger
fire
shin, shoulder, wrist