(noun)
a guard or some device, typically made of wire or straps, that is fastened over an animal's nose and mouth in order to prevent it from biting or eating;
e.g. The dog was put in a muzzle when it was taken on the train.
(noun)
the open (discharging) end of a firearm;
e.g. The robber pointed the muzzle of his gun at the people.
(noun)
some entity that restrains the free expression of ideas, e.g. censorship;
e.g. They tried to put a muzzle on the reporter so that the story would not be leaked.
(verb)
to prevent a person or entity from freely expressing their ideas and opinions, i.e. the restrict their expression;
e.g. The company tried to muzzle the media to prevent negative publicity.
(verb)
to place and fasten a covering over the nose and mouth of an animal to prevent it from biting or eating;
e.g. Visitors were asked to muzzle their pets before bringing them indoors.