Definitions of muzzle:

• noun:   forward projecting part of the head of certain animals; includes the jaws and nose
• noun:   a leather or wire restraint that fits over an animal's snout (especially a dog's nose and jaws) and prevents it from eating or biting
• noun:   restraint put into a person's mouth to prevent speaking or shouting
• noun:   the open circular discharging end of a gun
• verb:   fit with a muzzle

  Example: "Muzzle the dog to prevent it from biting strangers"

• verb:   prevent from speaking out
• verb:   tie a gag around someone's mouth in order to silence them