guard

a device designed to prevent injury or accidents

a posture of defence in boxing or fencing

“keep your guard up”

take precautions in order to avoid some unwanted consequence

“guard against becoming too friendly with the staff”

the person who plays that position on a football team

“the left guard was injured on the play”

the person who plays the position of guard on a basketball team

to keep watch over

“there would be men guarding the horses”

the duty of serving as a sentry

“he was on guard that night”

a precautionary measure warding off impending danger or damage or injury etc.

“an insurance policy is a good safeguard”

watch over or shield from danger or harm; protect

“guard my possessions while I'm away”

protect against a challenge or attack

a position on the line of scrimmage

“guards must be good blockers”

a military unit serving to protect some place or person