A person who protects something is called a guard. You might see a security guard at the mall, a crossing guard on the street outside a school, or a palace guard at Buckingham Palace.

To guard something is to watch over it or keep it from danger. You should ask someone to guard your backpack when you go to the restroom at the restaurant — or take it with you. The verb guard also means to protect against unintended consequences. To guard against overeating at the party, you could have a light snack before you go, so you aren't as tempted by all the delicious snacks and desserts.

Definitions of guard
  1. verb
    watch over or shield from danger or harm; protect
    guard my possessions while I'm away”
    synonyms: ward
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    watch over like a shepherd, as a teacher of her pupils
    type of:
    protect, secure
    shield from danger, injury, destruction, or damage
  2. verb
    keep watch over
    “there would be men guarding the horses”
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    patrol, police
    maintain the security of by carrying out a patrol
    keep guard, stand guard, stand sentinel, stand watch
    watch over so as to protect
    baby-sit, sit
    work or act as a baby-sitter
    take watchful responsibility for
    type of:
    follow, keep an eye on, observe, watch, watch over
    follow with the eyes or the mind
  3. verb
    protect against a challenge or attack
    synonyms: defend, hold
    take and maintain control over, often by violent means
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    type of:
    protect, secure
    shield from danger, injury, destruction, or damage
  4. noun
    a person who keeps watch over something or someone
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    bouncer, chucker-out
    a person whose duty is to throw troublemakers out of a bar or public meeting
    door guard, doorkeeper, doorman, gatekeeper, hall porter, ostiary, porter
    someone who guards an entrance
    a guard who carries a halberd (as a symbol of his duty)
    a guard at an airport who checks passengers or their luggage at a security checkpoint
    security guard, watcher, watchman
    a guard who keeps watch
    bank guard
    a security guard at a bank
    a uniformed doorman
    fire watcher
    (during World War II in Britain) someone whose duty was to watch for fires caused by bombs dropped from the air
    lookout, lookout man, picket, scout, sentinel, sentry, spotter, watch
    a person employed to keep watch for some anticipated event
    night porter
    a porter on duty during the night
    night watchman
    a watchman who works during the night
    someone on patrol duty; an individual or a member of a group that patrols an area
    port watcher, portwatcher
    a watchman on a wharf
    ticket collector, ticket taker
    someone who is paid to admit only those who have purchased tickets
    type of:
    defender, guardian, protector, shielder
    a person who cares for persons or property
  5. noun
    a military unit serving to protect some place or person
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    a group of men who escort and protect some important person
    home guard
    a volunteer unit formed to defend the homeland while the regular army is fighting elsewhere
    territorial, territorial reserve
    a territorial military unit
    a British volunteer cavalry force organized in 1761 for home defense later incorporated into the Territorial Army
    National Guard, home reserve
    United States military reserves recruited by the states and equipped by the federal government; subject to call by either
    Territorial Army
    British unit of nonprofessional soldiers organized for the defense of Great Britain
    Praetorian Guard
    the elite bodyguard of a Roman Emperor in ancient Rome
    type of:
    force, military force, military group, military unit
    a unit that is part of some military service
  6. noun
    the duty of serving as a sentry
    “he was on guard that night”
    synonyms: guard duty, sentry duty, sentry go
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    type of:
    assignment, duty assignment
    a duty that you are assigned to perform (especially in the armed forces)
  7. verb
    take precautions in order to avoid some unwanted consequence
    guard against becoming too friendly with the staff”
    guard against infection”
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    type of:
    act, move
    perform an action, or work out or perform (an action)
  8. noun
    a precautionary measure warding off impending danger or damage or injury etc.
    “we let our guard down”
    synonyms: precaution, safeguard
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    a precaution in case of an emergency
    security, security measures
    measures taken as a precaution against theft or espionage or sabotage etc.
    type of:
    measure, step
    any maneuver made as part of progress toward a goal
  9. noun
    a device designed to prevent injury or accidents
    synonyms: safety, safety device
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    a low metal guard to confine falling coals to a hearth
    safety catch, safety lock
    guard consisting of a locking device that prevents a weapon from being fired
    type of:
    an instrumentality invented for a particular purpose
  10. noun
    (American football) a position on the line of scrimmage
    guards must be good blockers”
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    type of:
    (American football) the position of a player on a football team who is stationed on the line of scrimmage
  11. noun
    the person who plays that position on a football team
    “the left guard was injured on the play”
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    type of:
    one of the players on the line of scrimmage
  12. noun
    a position on a basketball team
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    type of:
    (in team sports) the role assigned to an individual player
  13. noun
    the person who plays the position of guard on a basketball team
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    Oscar Palmer Robertson
    United States basketball guard (born in 1938)
    type of:
    basketball player, basketeer, cager
    an athlete who plays basketball
  14. noun
    a posture of defence in boxing or fencing
    “keep your guard up”
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    type of:
    attitude, position, posture
    the arrangement of the body and its limbs
Word Family

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