English▸ adjective
1 mainly Anatomy relating to the lips.
▪ Dentistry (of the surface of a tooth) adjacent to the lips.
▪ Zoology resembling or serving as a lip, liplike part, or labium.
2 Phonetics (of a consonant) requiring partial or complete closure of the lips (e.g. p, b, f, v, m, w), or (of a vowel) requiring rounded lips (e.g. oo in moon).
– ORIGIN late 16th century: from medieval Latin labialis, from Latin labium ‘lip’.