- Animal Behavior.
- in dogs, a lifting of the upper lip as a warning, either to humans or to other animals: In dog language, that lip curl is actually a peaceable signal—the dog is hoping the other dog understands that it wants to be left alone.
- in deer and other artiodactyls, horses, and felines, an upward curling of the upper lip to aid the sense of smell by increasing the flow of air through the nostrils and exposing the auxiliary olfactory organs: a characteristic component of the flehmen response and sometimes also a sign of pain or symptom of disease.
- in humans, an arching of one side of the upper lip, expressing either scorn or sexual interest: She could not speak of defectors and informers without a lip curl.He does a great Elvis impression—tantalizing lip curl and all.
