La″bi‐al (?), a. [LL. labialis, fr. L. labium lip: cf. F. labial. See Lip.] 1. Of or pertaining to the lips or labia; as, labial veins.
2. (Mus.) Furnished with lips; as, a labial organ pipe.
3. (Phonetics) (a) Articulated, as a consonant, mainly by the lips, as b, p, m, w. (b) Modified, as a vowel, by contraction of the lip opening, as o͞o (fo͞od), ō (ōld), etc., and as eu and u in French, and ö, ü in German. See Guide to Pronunciation, §§ 11, 178.
4. (Zoöl.) Of or pertaining to the labium; as, the labial palpi of insects. See Labium.