Bilabial, a term commonly used in linguistics, refers to a sound produced by the movement of both lips. Synonyms for bilabial include labial, bilabiate, bidental, and labio-dental. The labial sound is widely used in languages around the world, particularly in consonants such as "b", "m", and "p." When two opposing lips touch or come extremely close together, this produces a bilabial sound. The term "bilabiate" emphasizes the double lip movement involved in producing the sound. While "bidental" specifically refers to sounds that require the teeth to come together as well, the term "labio-dental" describes sounds that also require the tongue and teeth in addition to the lips.