bilabial

Bilabial is a term used in phonetics to describe a place of articulation for the production of speech sounds. The term derives from Latin bi meaning two, and labial meaning lips. A bilabial sound is produced with both lips, typically the upper and lower lips coming into contact or near contact. This distinguishes bilabial sounds from labiodental sounds (produced with the lower lip and upper teeth) and from other places of articulation such as dental, alveolar, velar, etc. The bilabial category is most commonly associated with consonants rather than vowels.

The most common bilabial consonants are the stops p and b, and the nasal m. In many languages these form the basic triad of voiceless, voiced, and nasal bilabials. Some languages also have bilabial fricatives, such as [ɸ] (voiceless) and [β] (voiced), and a bilabial approximant sometimes described in the literature, though the precise status of such sounds varies by analysis. The English language includes p, b, and m; it also has w, which is typically analyzed as a labio-velar approximant rather than a purely bilabial sound, since it involves both the lips and the soft palate.

Vowels generally do not have bilabial place of articulation; lip rounding is a distinct articulatory feature that accompanies many vowels rather than defining a place. Bilabial sounds occur in a wide range of languages and play a central role in many phoneme inventories, often near the beginning of the consonant series in phoneme inventories across languages.