The lips.
Latin labium, lip.
The adjective referring to the lips is labial. In phonetics several terms indicate a sound involving the lips, as in labiodental, with the lips and teeth, for example f and v, or labiovelar, with the lips and soft palate, for example w. A labium is a lip-like structure, say part of the mouth of an insect or the lower lip of the flower of a plant.
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