Definition of "Guard" :

noun: a position on a basketball team

noun: (American football) a position on the line of scrimmage

"Guards must be good blockers."

noun: the duty of serving as a sentry

"He was on guard that night."

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

"An insurance policy is a good safeguard."

noun: a device designed to prevent injury or accidents

noun: a posture of defence in boxing or fencing

"Keep your guard up."

noun: a military unit serving to protect some place or person

noun: the person who plays that position on a football team

"The left guard was injured on the play."

noun: a person who keeps watch over something or someone

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

verb: watch over or shield from danger or harm; protect

"Guard my possessions while I'm away."

verb: protect against a challenge or attack

verb: to keep watch over

"There would be men guarding the horses."

verb: take precautions in order to avoid some unwanted consequence

"Guard against becoming too friendly with the staff."