Snarl

A snarl is 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 and dogs snarl, often to warn others of their potential bite. In humans, snarling uses the levator labii superioris alaeque nasi muscle. Snarling is often accompanied by or used synonymously with threatening vocalizations (it may also be used as an onomatopoeia for a threatening noise, as in the 'snarl' of a chainsaw).The atrophy of this muscle with age makes sometime a symmetrical or asymmetrical Alar vertical retraction and accentuates the "tear trough. Then the nose looks always bigger when we age.

Also:–noun1. a tangle, as of thread, hair, or wire.2. a complicated or confused condition or matter: a traffic snarl.3. a knot in wood.–verb (used with object)4. to bring into a tangled condition, as thread or hair.5. to render complicated or confused: The questions snarled him up.6. to raise or emboss, as parts of a thin metal vessel, by hammering on a tool (snarling iron) held against the inner surface of the vessel.–verb (used without object)7. to become tangled; get into a tangle. [Origin: 1350–1400; ME snarle; see snare1, -le]