to keep safe from harm or danger; protect; watch over

to guard the ruler.

to keep under close watch in order to prevent escape, misconduct, etc.

to guard a prisoner.

to keep under control or restraint as a matter of caution or prudence

to guard one's temper.

to provide or equip with some safeguard or protective appliance, as to prevent loss, injury, etc.

Sports . to position oneself so as to obstruct or impede the movement or progress of (an opponent on offense)

The linebacker moved to his right to guard the end going out for a pass.

Chess . to protect (a piece or a square) by placing a piece in a supportive or defensive position relative to it.

to take precautions (usually fol. by against )

to guard against errors.

to give protection; keep watch; be watchful.

a person or group of persons that guards, protects, or keeps a protective or restraining watch.

a person who keeps watch over prisoners or others under restraint.

a body of people, esp. soldiers, charged with guarding a place from disturbance, theft, fire, etc.

a close watch, as over a prisoner or other person under restraint

to be kept under guard.

a device, appliance, or attachment that prevents injury, loss, etc.

something intended or serving to guard or protect; safeguard

insurance as a guard against disasters.

a posture of defense or readiness, as in fencing, boxing, or bayonet drill.

Football .

either of the linemen stationed between a tackle and the center.

the position played by this lineman.

Basketball . either of the players stationed in the backcourt.

Chess . a piece that supports or defends another.

Cards . a low card that is held with a high card of the same suit and that enables the holder to save the high card for a later trick.

British . a railroad conductor.

Guards, the name of certain bodies of troops in the British army. ?

off guard

unprepared; unwary

The blow from behind caught him off guard. Also, off one's guard.

on guard

vigilant; wary

on guard against dishonest merchants. Also, on one's guard.

stand guard over

to watch over; protect

The dog stood guard over his wounded master.

adjective

alert , averting , cautious , checking , defending , expectant , guarding , preservative , preventive , protecting , safeguarding , vigilant , warding off , watchful , withstanding

adverb

alert , careful , cautious , defensive , guarded , heedful , mindful , observant , on one\'s guard , on one\'s toes , on the lookout , on the watch , vigilant , wary , watchful