noun

1. A person who, or thing that, protects or watches over something.

   “The prison guard unlocked the door of the cell.   After completing the repairs, he replaced the sump guard.”

2. A garda; a police officer.

3. A squad responsible for protecting something.

   “The president inspected the guard of honour.”

Synonyms: fender, protection, quillon

verb

1. To protect from danger; to secure against surprise, attack, or injury; to keep in safety; to defend.

2. To keep watch over, in order to prevent escape or restrain from acts of violence, or the like.

   “Guard the prisoner.”

3. To watch by way of caution or defense; to be caution; to be in a state or position of defense or safety.

   “Careful people guard against mistakes.”