flehmen
noun
fleh·men ˈflā-mən 
: a mammalian behavior (as of horses or cats) in which the animal inhales with the mouth open and upper lip curled to facilitate exposure of the vomeronasal organ to a scent or pheromone
flehmen intransitive verb
Did you know?
Flehmen comes from German, in which the word applies to animals and means "to curl the upper lip." The German source of the English word is a verb, and it is used, infrequently, as such, as in "the horse flehmened." More often, the English verb form is a gerund: "the horse's flehmening." Flehmen is sometimes capitalized in English because German nouns are capitalized; however, the English word tends to be lowercase.
Word History
Etymology
German, from flehmen (of animals) to curl the upper lip
First Known Use
1970, in the meaning defined above