Real Dictionary

muzzle
countable noun: A muzzle is an object that is put over a dog's nose and mouth so that it cannot bite people or make a noise.
countable noun: The muzzle of a gun is the end where the bullets come out when it is fired.
countable noun: The muzzle of an animal such as a dog is its nose and mouth.
verb: If you muzzle a dog or other animal, you put a muzzle over its nose and mouth.
verb: If you say that someone is muzzled, you are complaining that they are prevented from expressing their views freely.

muzzle in American English
the projecting part of the head of a dog, horse, etc., including the mouth, nose, and jaws; snout
to put a muzzle on (an animal)
noun: the mouth, or end for discharge, of the barrel of a gun, pistol, etc
transitive verb: to put a muzzle on (an animal or its mouth) so as to prevent biting, eating, etc

muzzle in British English
to prevent from being heard or noticed
noun: the projecting part of the face, usually the jaws and nose, of animals such as the dog and horse