1. The forward, projecting part of the head of certain animals, such as dogs, including the mouth, nose, and jaws; the snout.
2. A leather or wire restraining appliance that, when fitted over an animal's snout, prevents biting and eating.
3. The forward, discharging end of the barrel of a firearm.
4. A restraint on free movement or expression: had a muzzle put on their high spirits.

1. To put a muzzle on (an animal).
2. To restrain from expression: tried to muzzle the opposition.

[Middle English mosel, from Old French musel, from Medieval Latin mūsellum, diminutive of mūsus, snout, from Latin mūsum.]

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.