snarl

right|frame|A facial expression which often accompanies a snarl thumb|right|The figure on the far right has a facial expression commonly associated with snarling.

A snarl is a sound, often a growl or vicious utterance, often accompanied by a facial expression, where the upper lip is raised, and the nostrils widen, generally indicating hate, anger or pain. In addition to humans, other mammals including monkeys, rabbits and dogs snarl, often to warn others of their potential bite. In humans, snarling uses the levator labii superioris alaeque nasi muscle. The threatening vocalizations of snarling are often accompanied by or used synonymously with threatening facial expressions.